mirror of
https://git.hardenedbsd.org/hardenedbsd/HardenedBSD.git
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aeff15b392
If 'td_lend_user_pri' has the expected value, there is no need to check
the fields that sched_lend_user_prio() modifies, they either are already
good or soon will be ('td->td_lend_user_pri' has just been changed by
a concurrent update).
Reviewed by: kib
Approved by: emaste (mentor)
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D44050
3352 lines
89 KiB
C
3352 lines
89 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2002-2007, Jeffrey Roberson <jeff@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* This file implements the ULE scheduler. ULE supports independent CPU
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* run queues and fine grain locking. It has superior interactive
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* performance under load even on uni-processor systems.
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*
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* etymology:
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* ULE is the last three letters in schedule. It owes its name to a
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* generic user created for a scheduling system by Paul Mikesell at
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* Isilon Systems and a general lack of creativity on the part of the author.
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*/
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#include <sys/cdefs.h>
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#include "opt_hwpmc_hooks.h"
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#include "opt_sched.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kdb.h>
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#include <sys/kernel.h>
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#include <sys/ktr.h>
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#include <sys/limits.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/resource.h>
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#include <sys/resourcevar.h>
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#include <sys/sched.h>
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#include <sys/sdt.h>
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#include <sys/smp.h>
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#include <sys/sx.h>
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#include <sys/sysctl.h>
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#include <sys/sysproto.h>
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#include <sys/turnstile.h>
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#include <sys/umtxvar.h>
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#include <sys/vmmeter.h>
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#include <sys/cpuset.h>
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#include <sys/sbuf.h>
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#ifdef HWPMC_HOOKS
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#include <sys/pmckern.h>
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#endif
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#ifdef KDTRACE_HOOKS
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#include <sys/dtrace_bsd.h>
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int __read_mostly dtrace_vtime_active;
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dtrace_vtime_switch_func_t dtrace_vtime_switch_func;
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#endif
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#include <machine/cpu.h>
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#include <machine/smp.h>
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#define KTR_ULE 0
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#define TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
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#define TDQ_NAME_LEN (sizeof("sched lock ") + sizeof(__XSTRING(MAXCPU)))
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#define TDQ_LOADNAME_LEN (sizeof("CPU ") + sizeof(__XSTRING(MAXCPU)) - 1 + sizeof(" load"))
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/*
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* Thread scheduler specific section. All fields are protected
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* by the thread lock.
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*/
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struct td_sched {
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struct runq *ts_runq; /* Run-queue we're queued on. */
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short ts_flags; /* TSF_* flags. */
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int ts_cpu; /* CPU that we have affinity for. */
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int ts_rltick; /* Real last tick, for affinity. */
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int ts_slice; /* Ticks of slice remaining. */
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u_int ts_slptime; /* Number of ticks we vol. slept */
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u_int ts_runtime; /* Number of ticks we were running */
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int ts_ltick; /* Last tick that we were running on */
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int ts_ftick; /* First tick that we were running on */
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int ts_ticks; /* Tick count */
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#ifdef KTR
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char ts_name[TS_NAME_LEN];
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#endif
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};
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/* flags kept in ts_flags */
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#define TSF_BOUND 0x0001 /* Thread can not migrate. */
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#define TSF_XFERABLE 0x0002 /* Thread was added as transferable. */
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#define THREAD_CAN_MIGRATE(td) ((td)->td_pinned == 0)
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#define THREAD_CAN_SCHED(td, cpu) \
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CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
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_Static_assert(sizeof(struct thread) + sizeof(struct td_sched) <=
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sizeof(struct thread0_storage),
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"increase struct thread0_storage.t0st_sched size");
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/*
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* Priority ranges used for interactive and non-interactive timeshare
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* threads. The timeshare priorities are split up into four ranges.
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* The first range handles interactive threads. The last three ranges
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* (NHALF, x, and NHALF) handle non-interactive threads with the outer
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* ranges supporting nice values.
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*/
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#define PRI_TIMESHARE_RANGE (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE + 1)
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#define PRI_INTERACT_RANGE ((PRI_TIMESHARE_RANGE - SCHED_PRI_NRESV) / 2)
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#define PRI_BATCH_RANGE (PRI_TIMESHARE_RANGE - PRI_INTERACT_RANGE)
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#define PRI_MIN_INTERACT PRI_MIN_TIMESHARE
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#define PRI_MAX_INTERACT (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE - 1)
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#define PRI_MIN_BATCH (PRI_MIN_TIMESHARE + PRI_INTERACT_RANGE)
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#define PRI_MAX_BATCH PRI_MAX_TIMESHARE
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/*
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* Cpu percentage computation macros and defines.
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*
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* SCHED_TICK_SECS: Number of seconds to average the cpu usage across.
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* SCHED_TICK_TARG: Number of hz ticks to average the cpu usage across.
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* SCHED_TICK_MAX: Maximum number of ticks before scaling back.
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* SCHED_TICK_SHIFT: Shift factor to avoid rounding away results.
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* SCHED_TICK_HZ: Compute the number of hz ticks for a given ticks count.
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* SCHED_TICK_TOTAL: Gives the amount of time we've been recording ticks.
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*/
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#define SCHED_TICK_SECS 10
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#define SCHED_TICK_TARG (hz * SCHED_TICK_SECS)
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#define SCHED_TICK_MAX (SCHED_TICK_TARG + hz)
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#define SCHED_TICK_SHIFT 10
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#define SCHED_TICK_HZ(ts) ((ts)->ts_ticks >> SCHED_TICK_SHIFT)
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#define SCHED_TICK_TOTAL(ts) (max((ts)->ts_ltick - (ts)->ts_ftick, hz))
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/*
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* These macros determine priorities for non-interactive threads. They are
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* assigned a priority based on their recent cpu utilization as expressed
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* by the ratio of ticks to the tick total. NHALF priorities at the start
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* and end of the MIN to MAX timeshare range are only reachable with negative
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* or positive nice respectively.
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*
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* PRI_RANGE: Priority range for utilization dependent priorities.
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* PRI_NRESV: Number of nice values.
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* PRI_TICKS: Compute a priority in PRI_RANGE from the ticks count and total.
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* PRI_NICE: Determines the part of the priority inherited from nice.
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*/
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#define SCHED_PRI_NRESV (PRIO_MAX - PRIO_MIN)
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#define SCHED_PRI_NHALF (SCHED_PRI_NRESV / 2)
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#define SCHED_PRI_MIN (PRI_MIN_BATCH + SCHED_PRI_NHALF)
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#define SCHED_PRI_MAX (PRI_MAX_BATCH - SCHED_PRI_NHALF)
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#define SCHED_PRI_RANGE (SCHED_PRI_MAX - SCHED_PRI_MIN + 1)
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#define SCHED_PRI_TICKS(ts) \
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(SCHED_TICK_HZ((ts)) / \
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(roundup(SCHED_TICK_TOTAL((ts)), SCHED_PRI_RANGE) / SCHED_PRI_RANGE))
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#define SCHED_PRI_NICE(nice) (nice)
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/*
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* These determine the interactivity of a process. Interactivity differs from
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* cpu utilization in that it expresses the voluntary time slept vs time ran
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* while cpu utilization includes all time not running. This more accurately
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* models the intent of the thread.
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*
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* SLP_RUN_MAX: Maximum amount of sleep time + run time we'll accumulate
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* before throttling back.
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* SLP_RUN_FORK: Maximum slp+run time to inherit at fork time.
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* INTERACT_MAX: Maximum interactivity value. Smaller is better.
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* INTERACT_THRESH: Threshold for placement on the current runq.
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*/
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#define SCHED_SLP_RUN_MAX ((hz * 5) << SCHED_TICK_SHIFT)
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#define SCHED_SLP_RUN_FORK ((hz / 2) << SCHED_TICK_SHIFT)
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#define SCHED_INTERACT_MAX (100)
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#define SCHED_INTERACT_HALF (SCHED_INTERACT_MAX / 2)
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#define SCHED_INTERACT_THRESH (30)
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/*
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* These parameters determine the slice behavior for batch work.
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*/
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#define SCHED_SLICE_DEFAULT_DIVISOR 10 /* ~94 ms, 12 stathz ticks. */
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#define SCHED_SLICE_MIN_DIVISOR 6 /* DEFAULT/MIN = ~16 ms. */
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/* Flags kept in td_flags. */
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#define TDF_PICKCPU TDF_SCHED0 /* Thread should pick new CPU. */
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#define TDF_SLICEEND TDF_SCHED2 /* Thread time slice is over. */
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/*
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* tickincr: Converts a stathz tick into a hz domain scaled by
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* the shift factor. Without the shift the error rate
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* due to rounding would be unacceptably high.
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* realstathz: stathz is sometimes 0 and run off of hz.
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* sched_slice: Runtime of each thread before rescheduling.
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* preempt_thresh: Priority threshold for preemption and remote IPIs.
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*/
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static u_int __read_mostly sched_interact = SCHED_INTERACT_THRESH;
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static int __read_mostly tickincr = 8 << SCHED_TICK_SHIFT;
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static int __read_mostly realstathz = 127; /* reset during boot. */
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static int __read_mostly sched_slice = 10; /* reset during boot. */
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static int __read_mostly sched_slice_min = 1; /* reset during boot. */
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#ifdef PREEMPTION
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#ifdef FULL_PREEMPTION
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static int __read_mostly preempt_thresh = PRI_MAX_IDLE;
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#else
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static int __read_mostly preempt_thresh = PRI_MIN_KERN;
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#endif
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#else
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static int __read_mostly preempt_thresh = 0;
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#endif
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static int __read_mostly static_boost = PRI_MIN_BATCH;
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static int __read_mostly sched_idlespins = 10000;
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static int __read_mostly sched_idlespinthresh = -1;
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/*
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* tdq - per processor runqs and statistics. A mutex synchronizes access to
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* most fields. Some fields are loaded or modified without the mutex.
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*
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* Locking protocols:
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* (c) constant after initialization
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* (f) flag, set with the tdq lock held, cleared on local CPU
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* (l) all accesses are CPU-local
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* (ls) stores are performed by the local CPU, loads may be lockless
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* (t) all accesses are protected by the tdq mutex
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* (ts) stores are serialized by the tdq mutex, loads may be lockless
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*/
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struct tdq {
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/*
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* Ordered to improve efficiency of cpu_search() and switch().
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* tdq_lock is padded to avoid false sharing with tdq_load and
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* tdq_cpu_idle.
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*/
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struct mtx_padalign tdq_lock; /* run queue lock. */
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struct cpu_group *tdq_cg; /* (c) Pointer to cpu topology. */
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struct thread *tdq_curthread; /* (t) Current executing thread. */
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int tdq_load; /* (ts) Aggregate load. */
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int tdq_sysload; /* (ts) For loadavg, !ITHD load. */
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int tdq_cpu_idle; /* (ls) cpu_idle() is active. */
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int tdq_transferable; /* (ts) Transferable thread count. */
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short tdq_switchcnt; /* (l) Switches this tick. */
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short tdq_oldswitchcnt; /* (l) Switches last tick. */
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u_char tdq_lowpri; /* (ts) Lowest priority thread. */
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u_char tdq_owepreempt; /* (f) Remote preemption pending. */
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u_char tdq_idx; /* (t) Current insert index. */
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u_char tdq_ridx; /* (t) Current removal index. */
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int tdq_id; /* (c) cpuid. */
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struct runq tdq_realtime; /* (t) real-time run queue. */
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struct runq tdq_timeshare; /* (t) timeshare run queue. */
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struct runq tdq_idle; /* (t) Queue of IDLE threads. */
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char tdq_name[TDQ_NAME_LEN];
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#ifdef KTR
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char tdq_loadname[TDQ_LOADNAME_LEN];
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#endif
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};
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/* Idle thread states and config. */
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#define TDQ_RUNNING 1
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#define TDQ_IDLE 2
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/* Lockless accessors. */
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#define TDQ_LOAD(tdq) atomic_load_int(&(tdq)->tdq_load)
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#define TDQ_TRANSFERABLE(tdq) atomic_load_int(&(tdq)->tdq_transferable)
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#define TDQ_SWITCHCNT(tdq) (atomic_load_short(&(tdq)->tdq_switchcnt) + \
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atomic_load_short(&(tdq)->tdq_oldswitchcnt))
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#define TDQ_SWITCHCNT_INC(tdq) (atomic_store_short(&(tdq)->tdq_switchcnt, \
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atomic_load_short(&(tdq)->tdq_switchcnt) + 1))
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#ifdef SMP
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struct cpu_group __read_mostly *cpu_top; /* CPU topology */
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#define SCHED_AFFINITY_DEFAULT (max(1, hz / 1000))
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#define SCHED_AFFINITY(ts, t) ((ts)->ts_rltick > ticks - ((t) * affinity))
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/*
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* Run-time tunables.
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*/
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static int rebalance = 1;
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static int balance_interval = 128; /* Default set in sched_initticks(). */
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static int __read_mostly affinity;
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static int __read_mostly steal_idle = 1;
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static int __read_mostly steal_thresh = 2;
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static int __read_mostly always_steal = 0;
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static int __read_mostly trysteal_limit = 2;
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/*
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* One thread queue per processor.
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*/
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static struct tdq __read_mostly *balance_tdq;
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static int balance_ticks;
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DPCPU_DEFINE_STATIC(struct tdq, tdq);
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DPCPU_DEFINE_STATIC(uint32_t, randomval);
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#define TDQ_SELF() ((struct tdq *)PCPU_GET(sched))
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#define TDQ_CPU(x) (DPCPU_ID_PTR((x), tdq))
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#define TDQ_ID(x) ((x)->tdq_id)
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#else /* !SMP */
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static struct tdq tdq_cpu;
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#define TDQ_ID(x) (0)
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#define TDQ_SELF() (&tdq_cpu)
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#define TDQ_CPU(x) (&tdq_cpu)
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#endif
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#define TDQ_LOCK_ASSERT(t, type) mtx_assert(TDQ_LOCKPTR((t)), (type))
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#define TDQ_LOCK(t) mtx_lock_spin(TDQ_LOCKPTR((t)))
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#define TDQ_LOCK_FLAGS(t, f) mtx_lock_spin_flags(TDQ_LOCKPTR((t)), (f))
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#define TDQ_TRYLOCK(t) mtx_trylock_spin(TDQ_LOCKPTR((t)))
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#define TDQ_TRYLOCK_FLAGS(t, f) mtx_trylock_spin_flags(TDQ_LOCKPTR((t)), (f))
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#define TDQ_UNLOCK(t) mtx_unlock_spin(TDQ_LOCKPTR((t)))
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#define TDQ_LOCKPTR(t) ((struct mtx *)(&(t)->tdq_lock))
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static void sched_setpreempt(int);
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static void sched_priority(struct thread *);
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static void sched_thread_priority(struct thread *, u_char);
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static int sched_interact_score(struct thread *);
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static void sched_interact_update(struct thread *);
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static void sched_interact_fork(struct thread *);
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static void sched_pctcpu_update(struct td_sched *, int);
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/* Operations on per processor queues */
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static struct thread *tdq_choose(struct tdq *);
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static void tdq_setup(struct tdq *, int i);
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static void tdq_load_add(struct tdq *, struct thread *);
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static void tdq_load_rem(struct tdq *, struct thread *);
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static __inline void tdq_runq_add(struct tdq *, struct thread *, int);
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static __inline void tdq_runq_rem(struct tdq *, struct thread *);
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static inline int sched_shouldpreempt(int, int, int);
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static void tdq_print(int cpu);
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static void runq_print(struct runq *rq);
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static int tdq_add(struct tdq *, struct thread *, int);
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#ifdef SMP
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static int tdq_move(struct tdq *, struct tdq *);
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static int tdq_idled(struct tdq *);
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static void tdq_notify(struct tdq *, int lowpri);
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static struct thread *tdq_steal(struct tdq *, int);
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static struct thread *runq_steal(struct runq *, int);
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static int sched_pickcpu(struct thread *, int);
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static void sched_balance(void);
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static bool sched_balance_pair(struct tdq *, struct tdq *);
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static inline struct tdq *sched_setcpu(struct thread *, int, int);
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static inline void thread_unblock_switch(struct thread *, struct mtx *);
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static int sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS);
|
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static int sysctl_kern_sched_topology_spec_internal(struct sbuf *sb,
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struct cpu_group *cg, int indent);
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#endif
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|
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static void sched_setup(void *dummy);
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SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
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|
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static void sched_initticks(void *dummy);
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SYSINIT(sched_initticks, SI_SUB_CLOCKS, SI_ORDER_THIRD, sched_initticks,
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NULL);
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|
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SDT_PROVIDER_DEFINE(sched);
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|
|
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SDT_PROBE_DEFINE3(sched, , , change__pri, "struct thread *",
|
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"struct proc *", "uint8_t");
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SDT_PROBE_DEFINE3(sched, , , dequeue, "struct thread *",
|
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"struct proc *", "void *");
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SDT_PROBE_DEFINE4(sched, , , enqueue, "struct thread *",
|
|
"struct proc *", "void *", "int");
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SDT_PROBE_DEFINE4(sched, , , lend__pri, "struct thread *",
|
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"struct proc *", "uint8_t", "struct thread *");
|
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SDT_PROBE_DEFINE2(sched, , , load__change, "int", "int");
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SDT_PROBE_DEFINE2(sched, , , off__cpu, "struct thread *",
|
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"struct proc *");
|
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SDT_PROBE_DEFINE(sched, , , on__cpu);
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SDT_PROBE_DEFINE(sched, , , remain__cpu);
|
|
SDT_PROBE_DEFINE2(sched, , , surrender, "struct thread *",
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"struct proc *");
|
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|
|
/*
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|
* Print the threads waiting on a run-queue.
|
|
*/
|
|
static void
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runq_print(struct runq *rq)
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|
{
|
|
struct rqhead *rqh;
|
|
struct thread *td;
|
|
int pri;
|
|
int j;
|
|
int i;
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|
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for (i = 0; i < RQB_LEN; i++) {
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printf("\t\trunq bits %d 0x%zx\n",
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i, rq->rq_status.rqb_bits[i]);
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for (j = 0; j < RQB_BPW; j++)
|
|
if (rq->rq_status.rqb_bits[i] & (1ul << j)) {
|
|
pri = j + (i << RQB_L2BPW);
|
|
rqh = &rq->rq_queues[pri];
|
|
TAILQ_FOREACH(td, rqh, td_runq) {
|
|
printf("\t\t\ttd %p(%s) priority %d rqindex %d pri %d\n",
|
|
td, td->td_name, td->td_priority,
|
|
td->td_rqindex, pri);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Print the status of a per-cpu thread queue. Should be a ddb show cmd.
|
|
*/
|
|
static void __unused
|
|
tdq_print(int cpu)
|
|
{
|
|
struct tdq *tdq;
|
|
|
|
tdq = TDQ_CPU(cpu);
|
|
|
|
printf("tdq %d:\n", TDQ_ID(tdq));
|
|
printf("\tlock %p\n", TDQ_LOCKPTR(tdq));
|
|
printf("\tLock name: %s\n", tdq->tdq_name);
|
|
printf("\tload: %d\n", tdq->tdq_load);
|
|
printf("\tswitch cnt: %d\n", tdq->tdq_switchcnt);
|
|
printf("\told switch cnt: %d\n", tdq->tdq_oldswitchcnt);
|
|
printf("\ttimeshare idx: %d\n", tdq->tdq_idx);
|
|
printf("\ttimeshare ridx: %d\n", tdq->tdq_ridx);
|
|
printf("\tload transferable: %d\n", tdq->tdq_transferable);
|
|
printf("\tlowest priority: %d\n", tdq->tdq_lowpri);
|
|
printf("\trealtime runq:\n");
|
|
runq_print(&tdq->tdq_realtime);
|
|
printf("\ttimeshare runq:\n");
|
|
runq_print(&tdq->tdq_timeshare);
|
|
printf("\tidle runq:\n");
|
|
runq_print(&tdq->tdq_idle);
|
|
}
|
|
|
|
static inline int
|
|
sched_shouldpreempt(int pri, int cpri, int remote)
|
|
{
|
|
/*
|
|
* If the new priority is not better than the current priority there is
|
|
* nothing to do.
|
|
*/
|
|
if (pri >= cpri)
|
|
return (0);
|
|
/*
|
|
* Always preempt idle.
|
|
*/
|
|
if (cpri >= PRI_MIN_IDLE)
|
|
return (1);
|
|
/*
|
|
* If preemption is disabled don't preempt others.
|
|
*/
|
|
if (preempt_thresh == 0)
|
|
return (0);
|
|
/*
|
|
* Preempt if we exceed the threshold.
|
|
*/
|
|
if (pri <= preempt_thresh)
|
|
return (1);
|
|
/*
|
|
* If we're interactive or better and there is non-interactive
|
|
* or worse running preempt only remote processors.
|
|
*/
|
|
if (remote && pri <= PRI_MAX_INTERACT && cpri > PRI_MAX_INTERACT)
|
|
return (1);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Add a thread to the actual run-queue. Keeps transferable counts up to
|
|
* date with what is actually on the run-queue. Selects the correct
|
|
* queue position for timeshare threads.
|
|
*/
|
|
static __inline void
|
|
tdq_runq_add(struct tdq *tdq, struct thread *td, int flags)
|
|
{
|
|
struct td_sched *ts;
|
|
u_char pri;
|
|
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
|
|
|
|
pri = td->td_priority;
|
|
ts = td_get_sched(td);
|
|
TD_SET_RUNQ(td);
|
|
if (THREAD_CAN_MIGRATE(td)) {
|
|
tdq->tdq_transferable++;
|
|
ts->ts_flags |= TSF_XFERABLE;
|
|
}
|
|
if (pri < PRI_MIN_BATCH) {
|
|
ts->ts_runq = &tdq->tdq_realtime;
|
|
} else if (pri <= PRI_MAX_BATCH) {
|
|
ts->ts_runq = &tdq->tdq_timeshare;
|
|
KASSERT(pri <= PRI_MAX_BATCH && pri >= PRI_MIN_BATCH,
|
|
("Invalid priority %d on timeshare runq", pri));
|
|
/*
|
|
* This queue contains only priorities between MIN and MAX
|
|
* batch. Use the whole queue to represent these values.
|
|
*/
|
|
if ((flags & (SRQ_BORROWING|SRQ_PREEMPTED)) == 0) {
|
|
pri = RQ_NQS * (pri - PRI_MIN_BATCH) / PRI_BATCH_RANGE;
|
|
pri = (pri + tdq->tdq_idx) % RQ_NQS;
|
|
/*
|
|
* This effectively shortens the queue by one so we
|
|
* can have a one slot difference between idx and
|
|
* ridx while we wait for threads to drain.
|
|
*/
|
|
if (tdq->tdq_ridx != tdq->tdq_idx &&
|
|
pri == tdq->tdq_ridx)
|
|
pri = (unsigned char)(pri - 1) % RQ_NQS;
|
|
} else
|
|
pri = tdq->tdq_ridx;
|
|
runq_add_pri(ts->ts_runq, td, pri, flags);
|
|
return;
|
|
} else
|
|
ts->ts_runq = &tdq->tdq_idle;
|
|
runq_add(ts->ts_runq, td, flags);
|
|
}
|
|
|
|
/*
|
|
* Remove a thread from a run-queue. This typically happens when a thread
|
|
* is selected to run. Running threads are not on the queue and the
|
|
* transferable count does not reflect them.
|
|
*/
|
|
static __inline void
|
|
tdq_runq_rem(struct tdq *tdq, struct thread *td)
|
|
{
|
|
struct td_sched *ts;
|
|
|
|
ts = td_get_sched(td);
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
|
|
KASSERT(ts->ts_runq != NULL,
|
|
("tdq_runq_remove: thread %p null ts_runq", td));
|
|
if (ts->ts_flags & TSF_XFERABLE) {
|
|
tdq->tdq_transferable--;
|
|
ts->ts_flags &= ~TSF_XFERABLE;
|
|
}
|
|
if (ts->ts_runq == &tdq->tdq_timeshare) {
|
|
if (tdq->tdq_idx != tdq->tdq_ridx)
|
|
runq_remove_idx(ts->ts_runq, td, &tdq->tdq_ridx);
|
|
else
|
|
runq_remove_idx(ts->ts_runq, td, NULL);
|
|
} else
|
|
runq_remove(ts->ts_runq, td);
|
|
}
|
|
|
|
/*
|
|
* Load is maintained for all threads RUNNING and ON_RUNQ. Add the load
|
|
* for this thread to the referenced thread queue.
|
|
*/
|
|
static void
|
|
tdq_load_add(struct tdq *tdq, struct thread *td)
|
|
{
|
|
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
|
|
|
|
tdq->tdq_load++;
|
|
if ((td->td_flags & TDF_NOLOAD) == 0)
|
|
tdq->tdq_sysload++;
|
|
KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
|
|
SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
|
|
}
|
|
|
|
/*
|
|
* Remove the load from a thread that is transitioning to a sleep state or
|
|
* exiting.
|
|
*/
|
|
static void
|
|
tdq_load_rem(struct tdq *tdq, struct thread *td)
|
|
{
|
|
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
|
|
KASSERT(tdq->tdq_load != 0,
|
|
("tdq_load_rem: Removing with 0 load on queue %d", TDQ_ID(tdq)));
|
|
|
|
tdq->tdq_load--;
|
|
if ((td->td_flags & TDF_NOLOAD) == 0)
|
|
tdq->tdq_sysload--;
|
|
KTR_COUNTER0(KTR_SCHED, "load", tdq->tdq_loadname, tdq->tdq_load);
|
|
SDT_PROBE2(sched, , , load__change, (int)TDQ_ID(tdq), tdq->tdq_load);
|
|
}
|
|
|
|
/*
|
|
* Bound timeshare latency by decreasing slice size as load increases. We
|
|
* consider the maximum latency as the sum of the threads waiting to run
|
|
* aside from curthread and target no more than sched_slice latency but
|
|
* no less than sched_slice_min runtime.
|
|
*/
|
|
static inline int
|
|
tdq_slice(struct tdq *tdq)
|
|
{
|
|
int load;
|
|
|
|
/*
|
|
* It is safe to use sys_load here because this is called from
|
|
* contexts where timeshare threads are running and so there
|
|
* cannot be higher priority load in the system.
|
|
*/
|
|
load = tdq->tdq_sysload - 1;
|
|
if (load >= SCHED_SLICE_MIN_DIVISOR)
|
|
return (sched_slice_min);
|
|
if (load <= 1)
|
|
return (sched_slice);
|
|
return (sched_slice / load);
|
|
}
|
|
|
|
/*
|
|
* Set lowpri to its exact value by searching the run-queue and
|
|
* evaluating curthread. curthread may be passed as an optimization.
|
|
*/
|
|
static void
|
|
tdq_setlowpri(struct tdq *tdq, struct thread *ctd)
|
|
{
|
|
struct thread *td;
|
|
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
if (ctd == NULL)
|
|
ctd = tdq->tdq_curthread;
|
|
td = tdq_choose(tdq);
|
|
if (td == NULL || td->td_priority > ctd->td_priority)
|
|
tdq->tdq_lowpri = ctd->td_priority;
|
|
else
|
|
tdq->tdq_lowpri = td->td_priority;
|
|
}
|
|
|
|
#ifdef SMP
|
|
/*
|
|
* We need some randomness. Implement a classic Linear Congruential
|
|
* Generator X_{n+1}=(aX_n+c) mod m. These values are optimized for
|
|
* m = 2^32, a = 69069 and c = 5. We only return the upper 16 bits
|
|
* of the random state (in the low bits of our answer) to keep
|
|
* the maximum randomness.
|
|
*/
|
|
static uint32_t
|
|
sched_random(void)
|
|
{
|
|
uint32_t *rndptr;
|
|
|
|
rndptr = DPCPU_PTR(randomval);
|
|
*rndptr = *rndptr * 69069 + 5;
|
|
|
|
return (*rndptr >> 16);
|
|
}
|
|
|
|
struct cpu_search {
|
|
cpuset_t *cs_mask; /* The mask of allowed CPUs to choose from. */
|
|
int cs_prefer; /* Prefer this CPU and groups including it. */
|
|
int cs_running; /* The thread is now running at cs_prefer. */
|
|
int cs_pri; /* Min priority for low. */
|
|
int cs_load; /* Max load for low, min load for high. */
|
|
int cs_trans; /* Min transferable load for high. */
|
|
};
|
|
|
|
struct cpu_search_res {
|
|
int csr_cpu; /* The best CPU found. */
|
|
int csr_load; /* The load of cs_cpu. */
|
|
};
|
|
|
|
/*
|
|
* Search the tree of cpu_groups for the lowest or highest loaded CPU.
|
|
* These routines actually compare the load on all paths through the tree
|
|
* and find the least loaded cpu on the least loaded path, which may differ
|
|
* from the least loaded cpu in the system. This balances work among caches
|
|
* and buses.
|
|
*/
|
|
static int
|
|
cpu_search_lowest(const struct cpu_group *cg, const struct cpu_search *s,
|
|
struct cpu_search_res *r)
|
|
{
|
|
struct cpu_search_res lr;
|
|
struct tdq *tdq;
|
|
int c, bload, l, load, p, total;
|
|
|
|
total = 0;
|
|
bload = INT_MAX;
|
|
r->csr_cpu = -1;
|
|
|
|
/* Loop through children CPU groups if there are any. */
|
|
if (cg->cg_children > 0) {
|
|
for (c = cg->cg_children - 1; c >= 0; c--) {
|
|
load = cpu_search_lowest(&cg->cg_child[c], s, &lr);
|
|
total += load;
|
|
|
|
/*
|
|
* When balancing do not prefer SMT groups with load >1.
|
|
* It allows round-robin between SMT groups with equal
|
|
* load within parent group for more fair scheduling.
|
|
*/
|
|
if (__predict_false(s->cs_running) &&
|
|
(cg->cg_child[c].cg_flags & CG_FLAG_THREAD) &&
|
|
load >= 128 && (load & 128) != 0)
|
|
load += 128;
|
|
|
|
if (lr.csr_cpu >= 0 && (load < bload ||
|
|
(load == bload && lr.csr_load < r->csr_load))) {
|
|
bload = load;
|
|
r->csr_cpu = lr.csr_cpu;
|
|
r->csr_load = lr.csr_load;
|
|
}
|
|
}
|
|
return (total);
|
|
}
|
|
|
|
/* Loop through children CPUs otherwise. */
|
|
for (c = cg->cg_last; c >= cg->cg_first; c--) {
|
|
if (!CPU_ISSET(c, &cg->cg_mask))
|
|
continue;
|
|
tdq = TDQ_CPU(c);
|
|
l = TDQ_LOAD(tdq);
|
|
if (c == s->cs_prefer) {
|
|
if (__predict_false(s->cs_running))
|
|
l--;
|
|
p = 128;
|
|
} else
|
|
p = 0;
|
|
load = l * 256;
|
|
total += load - p;
|
|
|
|
/*
|
|
* Check this CPU is acceptable.
|
|
* If the threads is already on the CPU, don't look on the TDQ
|
|
* priority, since it can be the priority of the thread itself.
|
|
*/
|
|
if (l > s->cs_load ||
|
|
(atomic_load_char(&tdq->tdq_lowpri) <= s->cs_pri &&
|
|
(!s->cs_running || c != s->cs_prefer)) ||
|
|
!CPU_ISSET(c, s->cs_mask))
|
|
continue;
|
|
|
|
/*
|
|
* When balancing do not prefer CPUs with load > 1.
|
|
* It allows round-robin between CPUs with equal load
|
|
* within the CPU group for more fair scheduling.
|
|
*/
|
|
if (__predict_false(s->cs_running) && l > 0)
|
|
p = 0;
|
|
|
|
load -= sched_random() % 128;
|
|
if (bload > load - p) {
|
|
bload = load - p;
|
|
r->csr_cpu = c;
|
|
r->csr_load = load;
|
|
}
|
|
}
|
|
return (total);
|
|
}
|
|
|
|
static int
|
|
cpu_search_highest(const struct cpu_group *cg, const struct cpu_search *s,
|
|
struct cpu_search_res *r)
|
|
{
|
|
struct cpu_search_res lr;
|
|
struct tdq *tdq;
|
|
int c, bload, l, load, total;
|
|
|
|
total = 0;
|
|
bload = INT_MIN;
|
|
r->csr_cpu = -1;
|
|
|
|
/* Loop through children CPU groups if there are any. */
|
|
if (cg->cg_children > 0) {
|
|
for (c = cg->cg_children - 1; c >= 0; c--) {
|
|
load = cpu_search_highest(&cg->cg_child[c], s, &lr);
|
|
total += load;
|
|
if (lr.csr_cpu >= 0 && (load > bload ||
|
|
(load == bload && lr.csr_load > r->csr_load))) {
|
|
bload = load;
|
|
r->csr_cpu = lr.csr_cpu;
|
|
r->csr_load = lr.csr_load;
|
|
}
|
|
}
|
|
return (total);
|
|
}
|
|
|
|
/* Loop through children CPUs otherwise. */
|
|
for (c = cg->cg_last; c >= cg->cg_first; c--) {
|
|
if (!CPU_ISSET(c, &cg->cg_mask))
|
|
continue;
|
|
tdq = TDQ_CPU(c);
|
|
l = TDQ_LOAD(tdq);
|
|
load = l * 256;
|
|
total += load;
|
|
|
|
/*
|
|
* Check this CPU is acceptable.
|
|
*/
|
|
if (l < s->cs_load || TDQ_TRANSFERABLE(tdq) < s->cs_trans ||
|
|
!CPU_ISSET(c, s->cs_mask))
|
|
continue;
|
|
|
|
load -= sched_random() % 256;
|
|
if (load > bload) {
|
|
bload = load;
|
|
r->csr_cpu = c;
|
|
}
|
|
}
|
|
r->csr_load = bload;
|
|
return (total);
|
|
}
|
|
|
|
/*
|
|
* Find the cpu with the least load via the least loaded path that has a
|
|
* lowpri greater than pri pri. A pri of -1 indicates any priority is
|
|
* acceptable.
|
|
*/
|
|
static inline int
|
|
sched_lowest(const struct cpu_group *cg, cpuset_t *mask, int pri, int maxload,
|
|
int prefer, int running)
|
|
{
|
|
struct cpu_search s;
|
|
struct cpu_search_res r;
|
|
|
|
s.cs_prefer = prefer;
|
|
s.cs_running = running;
|
|
s.cs_mask = mask;
|
|
s.cs_pri = pri;
|
|
s.cs_load = maxload;
|
|
cpu_search_lowest(cg, &s, &r);
|
|
return (r.csr_cpu);
|
|
}
|
|
|
|
/*
|
|
* Find the cpu with the highest load via the highest loaded path.
|
|
*/
|
|
static inline int
|
|
sched_highest(const struct cpu_group *cg, cpuset_t *mask, int minload,
|
|
int mintrans)
|
|
{
|
|
struct cpu_search s;
|
|
struct cpu_search_res r;
|
|
|
|
s.cs_mask = mask;
|
|
s.cs_load = minload;
|
|
s.cs_trans = mintrans;
|
|
cpu_search_highest(cg, &s, &r);
|
|
return (r.csr_cpu);
|
|
}
|
|
|
|
static void
|
|
sched_balance_group(struct cpu_group *cg)
|
|
{
|
|
struct tdq *tdq;
|
|
struct thread *td;
|
|
cpuset_t hmask, lmask;
|
|
int high, low, anylow;
|
|
|
|
CPU_FILL(&hmask);
|
|
for (;;) {
|
|
high = sched_highest(cg, &hmask, 1, 0);
|
|
/* Stop if there is no more CPU with transferrable threads. */
|
|
if (high == -1)
|
|
break;
|
|
CPU_CLR(high, &hmask);
|
|
CPU_COPY(&hmask, &lmask);
|
|
/* Stop if there is no more CPU left for low. */
|
|
if (CPU_EMPTY(&lmask))
|
|
break;
|
|
tdq = TDQ_CPU(high);
|
|
if (TDQ_LOAD(tdq) == 1) {
|
|
/*
|
|
* There is only one running thread. We can't move
|
|
* it from here, so tell it to pick new CPU by itself.
|
|
*/
|
|
TDQ_LOCK(tdq);
|
|
td = tdq->tdq_curthread;
|
|
if (td->td_lock == TDQ_LOCKPTR(tdq) &&
|
|
(td->td_flags & TDF_IDLETD) == 0 &&
|
|
THREAD_CAN_MIGRATE(td)) {
|
|
td->td_flags |= TDF_PICKCPU;
|
|
ast_sched_locked(td, TDA_SCHED);
|
|
if (high != curcpu)
|
|
ipi_cpu(high, IPI_AST);
|
|
}
|
|
TDQ_UNLOCK(tdq);
|
|
break;
|
|
}
|
|
anylow = 1;
|
|
nextlow:
|
|
if (TDQ_TRANSFERABLE(tdq) == 0)
|
|
continue;
|
|
low = sched_lowest(cg, &lmask, -1, TDQ_LOAD(tdq) - 1, high, 1);
|
|
/* Stop if we looked well and found no less loaded CPU. */
|
|
if (anylow && low == -1)
|
|
break;
|
|
/* Go to next high if we found no less loaded CPU. */
|
|
if (low == -1)
|
|
continue;
|
|
/* Transfer thread from high to low. */
|
|
if (sched_balance_pair(tdq, TDQ_CPU(low))) {
|
|
/* CPU that got thread can no longer be a donor. */
|
|
CPU_CLR(low, &hmask);
|
|
} else {
|
|
/*
|
|
* If failed, then there is no threads on high
|
|
* that can run on this low. Drop low from low
|
|
* mask and look for different one.
|
|
*/
|
|
CPU_CLR(low, &lmask);
|
|
anylow = 0;
|
|
goto nextlow;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
sched_balance(void)
|
|
{
|
|
struct tdq *tdq;
|
|
|
|
balance_ticks = max(balance_interval / 2, 1) +
|
|
(sched_random() % balance_interval);
|
|
tdq = TDQ_SELF();
|
|
TDQ_UNLOCK(tdq);
|
|
sched_balance_group(cpu_top);
|
|
TDQ_LOCK(tdq);
|
|
}
|
|
|
|
/*
|
|
* Lock two thread queues using their address to maintain lock order.
|
|
*/
|
|
static void
|
|
tdq_lock_pair(struct tdq *one, struct tdq *two)
|
|
{
|
|
if (one < two) {
|
|
TDQ_LOCK(one);
|
|
TDQ_LOCK_FLAGS(two, MTX_DUPOK);
|
|
} else {
|
|
TDQ_LOCK(two);
|
|
TDQ_LOCK_FLAGS(one, MTX_DUPOK);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Unlock two thread queues. Order is not important here.
|
|
*/
|
|
static void
|
|
tdq_unlock_pair(struct tdq *one, struct tdq *two)
|
|
{
|
|
TDQ_UNLOCK(one);
|
|
TDQ_UNLOCK(two);
|
|
}
|
|
|
|
/*
|
|
* Transfer load between two imbalanced thread queues. Returns true if a thread
|
|
* was moved between the queues, and false otherwise.
|
|
*/
|
|
static bool
|
|
sched_balance_pair(struct tdq *high, struct tdq *low)
|
|
{
|
|
int cpu, lowpri;
|
|
bool ret;
|
|
|
|
ret = false;
|
|
tdq_lock_pair(high, low);
|
|
|
|
/*
|
|
* Transfer a thread from high to low.
|
|
*/
|
|
if (high->tdq_transferable != 0 && high->tdq_load > low->tdq_load) {
|
|
lowpri = tdq_move(high, low);
|
|
if (lowpri != -1) {
|
|
/*
|
|
* In case the target isn't the current CPU notify it of
|
|
* the new load, possibly sending an IPI to force it to
|
|
* reschedule. Otherwise maybe schedule a preemption.
|
|
*/
|
|
cpu = TDQ_ID(low);
|
|
if (cpu != PCPU_GET(cpuid))
|
|
tdq_notify(low, lowpri);
|
|
else
|
|
sched_setpreempt(low->tdq_lowpri);
|
|
ret = true;
|
|
}
|
|
}
|
|
tdq_unlock_pair(high, low);
|
|
return (ret);
|
|
}
|
|
|
|
/*
|
|
* Move a thread from one thread queue to another. Returns -1 if the source
|
|
* queue was empty, else returns the maximum priority of all threads in
|
|
* the destination queue prior to the addition of the new thread. In the latter
|
|
* case, this priority can be used to determine whether an IPI needs to be
|
|
* delivered.
|
|
*/
|
|
static int
|
|
tdq_move(struct tdq *from, struct tdq *to)
|
|
{
|
|
struct thread *td;
|
|
int cpu;
|
|
|
|
TDQ_LOCK_ASSERT(from, MA_OWNED);
|
|
TDQ_LOCK_ASSERT(to, MA_OWNED);
|
|
|
|
cpu = TDQ_ID(to);
|
|
td = tdq_steal(from, cpu);
|
|
if (td == NULL)
|
|
return (-1);
|
|
|
|
/*
|
|
* Although the run queue is locked the thread may be
|
|
* blocked. We can not set the lock until it is unblocked.
|
|
*/
|
|
thread_lock_block_wait(td);
|
|
sched_rem(td);
|
|
THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(from));
|
|
td->td_lock = TDQ_LOCKPTR(to);
|
|
td_get_sched(td)->ts_cpu = cpu;
|
|
return (tdq_add(to, td, SRQ_YIELDING));
|
|
}
|
|
|
|
/*
|
|
* This tdq has idled. Try to steal a thread from another cpu and switch
|
|
* to it.
|
|
*/
|
|
static int
|
|
tdq_idled(struct tdq *tdq)
|
|
{
|
|
struct cpu_group *cg, *parent;
|
|
struct tdq *steal;
|
|
cpuset_t mask;
|
|
int cpu, switchcnt, goup;
|
|
|
|
if (smp_started == 0 || steal_idle == 0 || tdq->tdq_cg == NULL)
|
|
return (1);
|
|
CPU_FILL(&mask);
|
|
CPU_CLR(PCPU_GET(cpuid), &mask);
|
|
restart:
|
|
switchcnt = TDQ_SWITCHCNT(tdq);
|
|
for (cg = tdq->tdq_cg, goup = 0; ; ) {
|
|
cpu = sched_highest(cg, &mask, steal_thresh, 1);
|
|
/*
|
|
* We were assigned a thread but not preempted. Returning
|
|
* 0 here will cause our caller to switch to it.
|
|
*/
|
|
if (TDQ_LOAD(tdq))
|
|
return (0);
|
|
|
|
/*
|
|
* We found no CPU to steal from in this group. Escalate to
|
|
* the parent and repeat. But if parent has only two children
|
|
* groups we can avoid searching this group again by searching
|
|
* the other one specifically and then escalating two levels.
|
|
*/
|
|
if (cpu == -1) {
|
|
if (goup) {
|
|
cg = cg->cg_parent;
|
|
goup = 0;
|
|
}
|
|
parent = cg->cg_parent;
|
|
if (parent == NULL)
|
|
return (1);
|
|
if (parent->cg_children == 2) {
|
|
if (cg == &parent->cg_child[0])
|
|
cg = &parent->cg_child[1];
|
|
else
|
|
cg = &parent->cg_child[0];
|
|
goup = 1;
|
|
} else
|
|
cg = parent;
|
|
continue;
|
|
}
|
|
steal = TDQ_CPU(cpu);
|
|
/*
|
|
* The data returned by sched_highest() is stale and
|
|
* the chosen CPU no longer has an eligible thread.
|
|
*
|
|
* Testing this ahead of tdq_lock_pair() only catches
|
|
* this situation about 20% of the time on an 8 core
|
|
* 16 thread Ryzen 7, but it still helps performance.
|
|
*/
|
|
if (TDQ_LOAD(steal) < steal_thresh ||
|
|
TDQ_TRANSFERABLE(steal) == 0)
|
|
goto restart;
|
|
/*
|
|
* Try to lock both queues. If we are assigned a thread while
|
|
* waited for the lock, switch to it now instead of stealing.
|
|
* If we can't get the lock, then somebody likely got there
|
|
* first so continue searching.
|
|
*/
|
|
TDQ_LOCK(tdq);
|
|
if (tdq->tdq_load > 0) {
|
|
mi_switch(SW_VOL | SWT_IDLE);
|
|
return (0);
|
|
}
|
|
if (TDQ_TRYLOCK_FLAGS(steal, MTX_DUPOK) == 0) {
|
|
TDQ_UNLOCK(tdq);
|
|
CPU_CLR(cpu, &mask);
|
|
continue;
|
|
}
|
|
/*
|
|
* The data returned by sched_highest() is stale and
|
|
* the chosen CPU no longer has an eligible thread, or
|
|
* we were preempted and the CPU loading info may be out
|
|
* of date. The latter is rare. In either case restart
|
|
* the search.
|
|
*/
|
|
if (TDQ_LOAD(steal) < steal_thresh ||
|
|
TDQ_TRANSFERABLE(steal) == 0 ||
|
|
switchcnt != TDQ_SWITCHCNT(tdq)) {
|
|
tdq_unlock_pair(tdq, steal);
|
|
goto restart;
|
|
}
|
|
/*
|
|
* Steal the thread and switch to it.
|
|
*/
|
|
if (tdq_move(steal, tdq) != -1)
|
|
break;
|
|
/*
|
|
* We failed to acquire a thread even though it looked
|
|
* like one was available. This could be due to affinity
|
|
* restrictions or for other reasons. Loop again after
|
|
* removing this CPU from the set. The restart logic
|
|
* above does not restore this CPU to the set due to the
|
|
* likelyhood of failing here again.
|
|
*/
|
|
CPU_CLR(cpu, &mask);
|
|
tdq_unlock_pair(tdq, steal);
|
|
}
|
|
TDQ_UNLOCK(steal);
|
|
mi_switch(SW_VOL | SWT_IDLE);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Notify a remote cpu of new work. Sends an IPI if criteria are met.
|
|
*
|
|
* "lowpri" is the minimum scheduling priority among all threads on
|
|
* the queue prior to the addition of the new thread.
|
|
*/
|
|
static void
|
|
tdq_notify(struct tdq *tdq, int lowpri)
|
|
{
|
|
int cpu;
|
|
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
KASSERT(tdq->tdq_lowpri <= lowpri,
|
|
("tdq_notify: lowpri %d > tdq_lowpri %d", lowpri, tdq->tdq_lowpri));
|
|
|
|
if (tdq->tdq_owepreempt)
|
|
return;
|
|
|
|
/*
|
|
* Check to see if the newly added thread should preempt the one
|
|
* currently running.
|
|
*/
|
|
if (!sched_shouldpreempt(tdq->tdq_lowpri, lowpri, 1))
|
|
return;
|
|
|
|
/*
|
|
* Make sure that our caller's earlier update to tdq_load is
|
|
* globally visible before we read tdq_cpu_idle. Idle thread
|
|
* accesses both of them without locks, and the order is important.
|
|
*/
|
|
atomic_thread_fence_seq_cst();
|
|
|
|
/*
|
|
* Try to figure out if we can signal the idle thread instead of sending
|
|
* an IPI. This check is racy; at worst, we will deliever an IPI
|
|
* unnecessarily.
|
|
*/
|
|
cpu = TDQ_ID(tdq);
|
|
if (TD_IS_IDLETHREAD(tdq->tdq_curthread) &&
|
|
(atomic_load_int(&tdq->tdq_cpu_idle) == 0 || cpu_idle_wakeup(cpu)))
|
|
return;
|
|
|
|
/*
|
|
* The run queues have been updated, so any switch on the remote CPU
|
|
* will satisfy the preemption request.
|
|
*/
|
|
tdq->tdq_owepreempt = 1;
|
|
ipi_cpu(cpu, IPI_PREEMPT);
|
|
}
|
|
|
|
/*
|
|
* Steals load from a timeshare queue. Honors the rotating queue head
|
|
* index.
|
|
*/
|
|
static struct thread *
|
|
runq_steal_from(struct runq *rq, int cpu, u_char start)
|
|
{
|
|
struct rqbits *rqb;
|
|
struct rqhead *rqh;
|
|
struct thread *td, *first;
|
|
int bit;
|
|
int i;
|
|
|
|
rqb = &rq->rq_status;
|
|
bit = start & (RQB_BPW -1);
|
|
first = NULL;
|
|
again:
|
|
for (i = RQB_WORD(start); i < RQB_LEN; bit = 0, i++) {
|
|
if (rqb->rqb_bits[i] == 0)
|
|
continue;
|
|
if (bit == 0)
|
|
bit = RQB_FFS(rqb->rqb_bits[i]);
|
|
for (; bit < RQB_BPW; bit++) {
|
|
if ((rqb->rqb_bits[i] & (1ul << bit)) == 0)
|
|
continue;
|
|
rqh = &rq->rq_queues[bit + (i << RQB_L2BPW)];
|
|
TAILQ_FOREACH(td, rqh, td_runq) {
|
|
if (first) {
|
|
if (THREAD_CAN_MIGRATE(td) &&
|
|
THREAD_CAN_SCHED(td, cpu))
|
|
return (td);
|
|
} else
|
|
first = td;
|
|
}
|
|
}
|
|
}
|
|
if (start != 0) {
|
|
start = 0;
|
|
goto again;
|
|
}
|
|
|
|
if (first && THREAD_CAN_MIGRATE(first) &&
|
|
THREAD_CAN_SCHED(first, cpu))
|
|
return (first);
|
|
return (NULL);
|
|
}
|
|
|
|
/*
|
|
* Steals load from a standard linear queue.
|
|
*/
|
|
static struct thread *
|
|
runq_steal(struct runq *rq, int cpu)
|
|
{
|
|
struct rqhead *rqh;
|
|
struct rqbits *rqb;
|
|
struct thread *td;
|
|
int word;
|
|
int bit;
|
|
|
|
rqb = &rq->rq_status;
|
|
for (word = 0; word < RQB_LEN; word++) {
|
|
if (rqb->rqb_bits[word] == 0)
|
|
continue;
|
|
for (bit = 0; bit < RQB_BPW; bit++) {
|
|
if ((rqb->rqb_bits[word] & (1ul << bit)) == 0)
|
|
continue;
|
|
rqh = &rq->rq_queues[bit + (word << RQB_L2BPW)];
|
|
TAILQ_FOREACH(td, rqh, td_runq)
|
|
if (THREAD_CAN_MIGRATE(td) &&
|
|
THREAD_CAN_SCHED(td, cpu))
|
|
return (td);
|
|
}
|
|
}
|
|
return (NULL);
|
|
}
|
|
|
|
/*
|
|
* Attempt to steal a thread in priority order from a thread queue.
|
|
*/
|
|
static struct thread *
|
|
tdq_steal(struct tdq *tdq, int cpu)
|
|
{
|
|
struct thread *td;
|
|
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
if ((td = runq_steal(&tdq->tdq_realtime, cpu)) != NULL)
|
|
return (td);
|
|
if ((td = runq_steal_from(&tdq->tdq_timeshare,
|
|
cpu, tdq->tdq_ridx)) != NULL)
|
|
return (td);
|
|
return (runq_steal(&tdq->tdq_idle, cpu));
|
|
}
|
|
|
|
/*
|
|
* Sets the thread lock and ts_cpu to match the requested cpu. Unlocks the
|
|
* current lock and returns with the assigned queue locked.
|
|
*/
|
|
static inline struct tdq *
|
|
sched_setcpu(struct thread *td, int cpu, int flags)
|
|
{
|
|
|
|
struct tdq *tdq;
|
|
struct mtx *mtx;
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
tdq = TDQ_CPU(cpu);
|
|
td_get_sched(td)->ts_cpu = cpu;
|
|
/*
|
|
* If the lock matches just return the queue.
|
|
*/
|
|
if (td->td_lock == TDQ_LOCKPTR(tdq)) {
|
|
KASSERT((flags & SRQ_HOLD) == 0,
|
|
("sched_setcpu: Invalid lock for SRQ_HOLD"));
|
|
return (tdq);
|
|
}
|
|
|
|
/*
|
|
* The hard case, migration, we need to block the thread first to
|
|
* prevent order reversals with other cpus locks.
|
|
*/
|
|
spinlock_enter();
|
|
mtx = thread_lock_block(td);
|
|
if ((flags & SRQ_HOLD) == 0)
|
|
mtx_unlock_spin(mtx);
|
|
TDQ_LOCK(tdq);
|
|
thread_lock_unblock(td, TDQ_LOCKPTR(tdq));
|
|
spinlock_exit();
|
|
return (tdq);
|
|
}
|
|
|
|
SCHED_STAT_DEFINE(pickcpu_intrbind, "Soft interrupt binding");
|
|
SCHED_STAT_DEFINE(pickcpu_idle_affinity, "Picked idle cpu based on affinity");
|
|
SCHED_STAT_DEFINE(pickcpu_affinity, "Picked cpu based on affinity");
|
|
SCHED_STAT_DEFINE(pickcpu_lowest, "Selected lowest load");
|
|
SCHED_STAT_DEFINE(pickcpu_local, "Migrated to current cpu");
|
|
SCHED_STAT_DEFINE(pickcpu_migration, "Selection may have caused migration");
|
|
|
|
static int
|
|
sched_pickcpu(struct thread *td, int flags)
|
|
{
|
|
struct cpu_group *cg, *ccg;
|
|
struct td_sched *ts;
|
|
struct tdq *tdq;
|
|
cpuset_t *mask;
|
|
int cpu, pri, r, self, intr;
|
|
|
|
self = PCPU_GET(cpuid);
|
|
ts = td_get_sched(td);
|
|
KASSERT(!CPU_ABSENT(ts->ts_cpu), ("sched_pickcpu: Start scheduler on "
|
|
"absent CPU %d for thread %s.", ts->ts_cpu, td->td_name));
|
|
if (smp_started == 0)
|
|
return (self);
|
|
/*
|
|
* Don't migrate a running thread from sched_switch().
|
|
*/
|
|
if ((flags & SRQ_OURSELF) || !THREAD_CAN_MIGRATE(td))
|
|
return (ts->ts_cpu);
|
|
/*
|
|
* Prefer to run interrupt threads on the processors that generate
|
|
* the interrupt.
|
|
*/
|
|
if (td->td_priority <= PRI_MAX_ITHD && THREAD_CAN_SCHED(td, self) &&
|
|
curthread->td_intr_nesting_level) {
|
|
tdq = TDQ_SELF();
|
|
if (tdq->tdq_lowpri >= PRI_MIN_IDLE) {
|
|
SCHED_STAT_INC(pickcpu_idle_affinity);
|
|
return (self);
|
|
}
|
|
ts->ts_cpu = self;
|
|
intr = 1;
|
|
cg = tdq->tdq_cg;
|
|
goto llc;
|
|
} else {
|
|
intr = 0;
|
|
tdq = TDQ_CPU(ts->ts_cpu);
|
|
cg = tdq->tdq_cg;
|
|
}
|
|
/*
|
|
* If the thread can run on the last cpu and the affinity has not
|
|
* expired and it is idle, run it there.
|
|
*/
|
|
if (THREAD_CAN_SCHED(td, ts->ts_cpu) &&
|
|
atomic_load_char(&tdq->tdq_lowpri) >= PRI_MIN_IDLE &&
|
|
SCHED_AFFINITY(ts, CG_SHARE_L2)) {
|
|
if (cg->cg_flags & CG_FLAG_THREAD) {
|
|
/* Check all SMT threads for being idle. */
|
|
for (cpu = cg->cg_first; cpu <= cg->cg_last; cpu++) {
|
|
pri =
|
|
atomic_load_char(&TDQ_CPU(cpu)->tdq_lowpri);
|
|
if (CPU_ISSET(cpu, &cg->cg_mask) &&
|
|
pri < PRI_MIN_IDLE)
|
|
break;
|
|
}
|
|
if (cpu > cg->cg_last) {
|
|
SCHED_STAT_INC(pickcpu_idle_affinity);
|
|
return (ts->ts_cpu);
|
|
}
|
|
} else {
|
|
SCHED_STAT_INC(pickcpu_idle_affinity);
|
|
return (ts->ts_cpu);
|
|
}
|
|
}
|
|
llc:
|
|
/*
|
|
* Search for the last level cache CPU group in the tree.
|
|
* Skip SMT, identical groups and caches with expired affinity.
|
|
* Interrupt threads affinity is explicit and never expires.
|
|
*/
|
|
for (ccg = NULL; cg != NULL; cg = cg->cg_parent) {
|
|
if (cg->cg_flags & CG_FLAG_THREAD)
|
|
continue;
|
|
if (cg->cg_children == 1 || cg->cg_count == 1)
|
|
continue;
|
|
if (cg->cg_level == CG_SHARE_NONE ||
|
|
(!intr && !SCHED_AFFINITY(ts, cg->cg_level)))
|
|
continue;
|
|
ccg = cg;
|
|
}
|
|
/* Found LLC shared by all CPUs, so do a global search. */
|
|
if (ccg == cpu_top)
|
|
ccg = NULL;
|
|
cpu = -1;
|
|
mask = &td->td_cpuset->cs_mask;
|
|
pri = td->td_priority;
|
|
r = TD_IS_RUNNING(td);
|
|
/*
|
|
* Try hard to keep interrupts within found LLC. Search the LLC for
|
|
* the least loaded CPU we can run now. For NUMA systems it should
|
|
* be within target domain, and it also reduces scheduling overhead.
|
|
*/
|
|
if (ccg != NULL && intr) {
|
|
cpu = sched_lowest(ccg, mask, pri, INT_MAX, ts->ts_cpu, r);
|
|
if (cpu >= 0)
|
|
SCHED_STAT_INC(pickcpu_intrbind);
|
|
} else
|
|
/* Search the LLC for the least loaded idle CPU we can run now. */
|
|
if (ccg != NULL) {
|
|
cpu = sched_lowest(ccg, mask, max(pri, PRI_MAX_TIMESHARE),
|
|
INT_MAX, ts->ts_cpu, r);
|
|
if (cpu >= 0)
|
|
SCHED_STAT_INC(pickcpu_affinity);
|
|
}
|
|
/* Search globally for the least loaded CPU we can run now. */
|
|
if (cpu < 0) {
|
|
cpu = sched_lowest(cpu_top, mask, pri, INT_MAX, ts->ts_cpu, r);
|
|
if (cpu >= 0)
|
|
SCHED_STAT_INC(pickcpu_lowest);
|
|
}
|
|
/* Search globally for the least loaded CPU. */
|
|
if (cpu < 0) {
|
|
cpu = sched_lowest(cpu_top, mask, -1, INT_MAX, ts->ts_cpu, r);
|
|
if (cpu >= 0)
|
|
SCHED_STAT_INC(pickcpu_lowest);
|
|
}
|
|
KASSERT(cpu >= 0, ("sched_pickcpu: Failed to find a cpu."));
|
|
KASSERT(!CPU_ABSENT(cpu), ("sched_pickcpu: Picked absent CPU %d.", cpu));
|
|
/*
|
|
* Compare the lowest loaded cpu to current cpu.
|
|
*/
|
|
tdq = TDQ_CPU(cpu);
|
|
if (THREAD_CAN_SCHED(td, self) && TDQ_SELF()->tdq_lowpri > pri &&
|
|
atomic_load_char(&tdq->tdq_lowpri) < PRI_MIN_IDLE &&
|
|
TDQ_LOAD(TDQ_SELF()) <= TDQ_LOAD(tdq) + 1) {
|
|
SCHED_STAT_INC(pickcpu_local);
|
|
cpu = self;
|
|
}
|
|
if (cpu != ts->ts_cpu)
|
|
SCHED_STAT_INC(pickcpu_migration);
|
|
return (cpu);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Pick the highest priority task we have and return it.
|
|
*/
|
|
static struct thread *
|
|
tdq_choose(struct tdq *tdq)
|
|
{
|
|
struct thread *td;
|
|
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
td = runq_choose(&tdq->tdq_realtime);
|
|
if (td != NULL)
|
|
return (td);
|
|
td = runq_choose_from(&tdq->tdq_timeshare, tdq->tdq_ridx);
|
|
if (td != NULL) {
|
|
KASSERT(td->td_priority >= PRI_MIN_BATCH,
|
|
("tdq_choose: Invalid priority on timeshare queue %d",
|
|
td->td_priority));
|
|
return (td);
|
|
}
|
|
td = runq_choose(&tdq->tdq_idle);
|
|
if (td != NULL) {
|
|
KASSERT(td->td_priority >= PRI_MIN_IDLE,
|
|
("tdq_choose: Invalid priority on idle queue %d",
|
|
td->td_priority));
|
|
return (td);
|
|
}
|
|
|
|
return (NULL);
|
|
}
|
|
|
|
/*
|
|
* Initialize a thread queue.
|
|
*/
|
|
static void
|
|
tdq_setup(struct tdq *tdq, int id)
|
|
{
|
|
|
|
if (bootverbose)
|
|
printf("ULE: setup cpu %d\n", id);
|
|
runq_init(&tdq->tdq_realtime);
|
|
runq_init(&tdq->tdq_timeshare);
|
|
runq_init(&tdq->tdq_idle);
|
|
tdq->tdq_id = id;
|
|
snprintf(tdq->tdq_name, sizeof(tdq->tdq_name),
|
|
"sched lock %d", (int)TDQ_ID(tdq));
|
|
mtx_init(&tdq->tdq_lock, tdq->tdq_name, "sched lock", MTX_SPIN);
|
|
#ifdef KTR
|
|
snprintf(tdq->tdq_loadname, sizeof(tdq->tdq_loadname),
|
|
"CPU %d load", (int)TDQ_ID(tdq));
|
|
#endif
|
|
}
|
|
|
|
#ifdef SMP
|
|
static void
|
|
sched_setup_smp(void)
|
|
{
|
|
struct tdq *tdq;
|
|
int i;
|
|
|
|
cpu_top = smp_topo();
|
|
CPU_FOREACH(i) {
|
|
tdq = DPCPU_ID_PTR(i, tdq);
|
|
tdq_setup(tdq, i);
|
|
tdq->tdq_cg = smp_topo_find(cpu_top, i);
|
|
if (tdq->tdq_cg == NULL)
|
|
panic("Can't find cpu group for %d\n", i);
|
|
DPCPU_ID_SET(i, randomval, i * 69069 + 5);
|
|
}
|
|
PCPU_SET(sched, DPCPU_PTR(tdq));
|
|
balance_tdq = TDQ_SELF();
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Setup the thread queues and initialize the topology based on MD
|
|
* information.
|
|
*/
|
|
static void
|
|
sched_setup(void *dummy)
|
|
{
|
|
struct tdq *tdq;
|
|
|
|
#ifdef SMP
|
|
sched_setup_smp();
|
|
#else
|
|
tdq_setup(TDQ_SELF(), 0);
|
|
#endif
|
|
tdq = TDQ_SELF();
|
|
|
|
/* Add thread0's load since it's running. */
|
|
TDQ_LOCK(tdq);
|
|
thread0.td_lock = TDQ_LOCKPTR(tdq);
|
|
tdq_load_add(tdq, &thread0);
|
|
tdq->tdq_curthread = &thread0;
|
|
tdq->tdq_lowpri = thread0.td_priority;
|
|
TDQ_UNLOCK(tdq);
|
|
}
|
|
|
|
/*
|
|
* This routine determines time constants after stathz and hz are setup.
|
|
*/
|
|
/* ARGSUSED */
|
|
static void
|
|
sched_initticks(void *dummy)
|
|
{
|
|
int incr;
|
|
|
|
realstathz = stathz ? stathz : hz;
|
|
sched_slice = realstathz / SCHED_SLICE_DEFAULT_DIVISOR;
|
|
sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
|
|
hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
|
|
realstathz);
|
|
|
|
/*
|
|
* tickincr is shifted out by 10 to avoid rounding errors due to
|
|
* hz not being evenly divisible by stathz on all platforms.
|
|
*/
|
|
incr = (hz << SCHED_TICK_SHIFT) / realstathz;
|
|
/*
|
|
* This does not work for values of stathz that are more than
|
|
* 1 << SCHED_TICK_SHIFT * hz. In practice this does not happen.
|
|
*/
|
|
if (incr == 0)
|
|
incr = 1;
|
|
tickincr = incr;
|
|
#ifdef SMP
|
|
/*
|
|
* Set the default balance interval now that we know
|
|
* what realstathz is.
|
|
*/
|
|
balance_interval = realstathz;
|
|
balance_ticks = balance_interval;
|
|
affinity = SCHED_AFFINITY_DEFAULT;
|
|
#endif
|
|
if (sched_idlespinthresh < 0)
|
|
sched_idlespinthresh = 2 * max(10000, 6 * hz) / realstathz;
|
|
}
|
|
|
|
/*
|
|
* This is the core of the interactivity algorithm. Determines a score based
|
|
* on past behavior. It is the ratio of sleep time to run time scaled to
|
|
* a [0, 100] integer. This is the voluntary sleep time of a process, which
|
|
* differs from the cpu usage because it does not account for time spent
|
|
* waiting on a run-queue. Would be prettier if we had floating point.
|
|
*
|
|
* When a thread's sleep time is greater than its run time the
|
|
* calculation is:
|
|
*
|
|
* scaling factor
|
|
* interactivity score = ---------------------
|
|
* sleep time / run time
|
|
*
|
|
*
|
|
* When a thread's run time is greater than its sleep time the
|
|
* calculation is:
|
|
*
|
|
* scaling factor
|
|
* interactivity score = 2 * scaling factor - ---------------------
|
|
* run time / sleep time
|
|
*/
|
|
static int
|
|
sched_interact_score(struct thread *td)
|
|
{
|
|
struct td_sched *ts;
|
|
int div;
|
|
|
|
ts = td_get_sched(td);
|
|
/*
|
|
* The score is only needed if this is likely to be an interactive
|
|
* task. Don't go through the expense of computing it if there's
|
|
* no chance.
|
|
*/
|
|
if (sched_interact <= SCHED_INTERACT_HALF &&
|
|
ts->ts_runtime >= ts->ts_slptime)
|
|
return (SCHED_INTERACT_HALF);
|
|
|
|
if (ts->ts_runtime > ts->ts_slptime) {
|
|
div = max(1, ts->ts_runtime / SCHED_INTERACT_HALF);
|
|
return (SCHED_INTERACT_HALF +
|
|
(SCHED_INTERACT_HALF - (ts->ts_slptime / div)));
|
|
}
|
|
if (ts->ts_slptime > ts->ts_runtime) {
|
|
div = max(1, ts->ts_slptime / SCHED_INTERACT_HALF);
|
|
return (ts->ts_runtime / div);
|
|
}
|
|
/* runtime == slptime */
|
|
if (ts->ts_runtime)
|
|
return (SCHED_INTERACT_HALF);
|
|
|
|
/*
|
|
* This can happen if slptime and runtime are 0.
|
|
*/
|
|
return (0);
|
|
|
|
}
|
|
|
|
/*
|
|
* Scale the scheduling priority according to the "interactivity" of this
|
|
* process.
|
|
*/
|
|
static void
|
|
sched_priority(struct thread *td)
|
|
{
|
|
u_int pri, score;
|
|
|
|
if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
|
|
return;
|
|
/*
|
|
* If the score is interactive we place the thread in the realtime
|
|
* queue with a priority that is less than kernel and interrupt
|
|
* priorities. These threads are not subject to nice restrictions.
|
|
*
|
|
* Scores greater than this are placed on the normal timeshare queue
|
|
* where the priority is partially decided by the most recent cpu
|
|
* utilization and the rest is decided by nice value.
|
|
*
|
|
* The nice value of the process has a linear effect on the calculated
|
|
* score. Negative nice values make it easier for a thread to be
|
|
* considered interactive.
|
|
*/
|
|
score = imax(0, sched_interact_score(td) + td->td_proc->p_nice);
|
|
if (score < sched_interact) {
|
|
pri = PRI_MIN_INTERACT;
|
|
pri += (PRI_MAX_INTERACT - PRI_MIN_INTERACT + 1) * score /
|
|
sched_interact;
|
|
KASSERT(pri >= PRI_MIN_INTERACT && pri <= PRI_MAX_INTERACT,
|
|
("sched_priority: invalid interactive priority %u score %u",
|
|
pri, score));
|
|
} else {
|
|
pri = SCHED_PRI_MIN;
|
|
if (td_get_sched(td)->ts_ticks)
|
|
pri += min(SCHED_PRI_TICKS(td_get_sched(td)),
|
|
SCHED_PRI_RANGE - 1);
|
|
pri += SCHED_PRI_NICE(td->td_proc->p_nice);
|
|
KASSERT(pri >= PRI_MIN_BATCH && pri <= PRI_MAX_BATCH,
|
|
("sched_priority: invalid priority %u: nice %d, "
|
|
"ticks %d ftick %d ltick %d tick pri %d",
|
|
pri, td->td_proc->p_nice, td_get_sched(td)->ts_ticks,
|
|
td_get_sched(td)->ts_ftick, td_get_sched(td)->ts_ltick,
|
|
SCHED_PRI_TICKS(td_get_sched(td))));
|
|
}
|
|
sched_user_prio(td, pri);
|
|
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* This routine enforces a maximum limit on the amount of scheduling history
|
|
* kept. It is called after either the slptime or runtime is adjusted. This
|
|
* function is ugly due to integer math.
|
|
*/
|
|
static void
|
|
sched_interact_update(struct thread *td)
|
|
{
|
|
struct td_sched *ts;
|
|
u_int sum;
|
|
|
|
ts = td_get_sched(td);
|
|
sum = ts->ts_runtime + ts->ts_slptime;
|
|
if (sum < SCHED_SLP_RUN_MAX)
|
|
return;
|
|
/*
|
|
* This only happens from two places:
|
|
* 1) We have added an unusual amount of run time from fork_exit.
|
|
* 2) We have added an unusual amount of sleep time from sched_sleep().
|
|
*/
|
|
if (sum > SCHED_SLP_RUN_MAX * 2) {
|
|
if (ts->ts_runtime > ts->ts_slptime) {
|
|
ts->ts_runtime = SCHED_SLP_RUN_MAX;
|
|
ts->ts_slptime = 1;
|
|
} else {
|
|
ts->ts_slptime = SCHED_SLP_RUN_MAX;
|
|
ts->ts_runtime = 1;
|
|
}
|
|
return;
|
|
}
|
|
/*
|
|
* If we have exceeded by more than 1/5th then the algorithm below
|
|
* will not bring us back into range. Dividing by two here forces
|
|
* us into the range of [4/5 * SCHED_INTERACT_MAX, SCHED_INTERACT_MAX]
|
|
*/
|
|
if (sum > (SCHED_SLP_RUN_MAX / 5) * 6) {
|
|
ts->ts_runtime /= 2;
|
|
ts->ts_slptime /= 2;
|
|
return;
|
|
}
|
|
ts->ts_runtime = (ts->ts_runtime / 5) * 4;
|
|
ts->ts_slptime = (ts->ts_slptime / 5) * 4;
|
|
}
|
|
|
|
/*
|
|
* Scale back the interactivity history when a child thread is created. The
|
|
* history is inherited from the parent but the thread may behave totally
|
|
* differently. For example, a shell spawning a compiler process. We want
|
|
* to learn that the compiler is behaving badly very quickly.
|
|
*/
|
|
static void
|
|
sched_interact_fork(struct thread *td)
|
|
{
|
|
struct td_sched *ts;
|
|
int ratio;
|
|
int sum;
|
|
|
|
ts = td_get_sched(td);
|
|
sum = ts->ts_runtime + ts->ts_slptime;
|
|
if (sum > SCHED_SLP_RUN_FORK) {
|
|
ratio = sum / SCHED_SLP_RUN_FORK;
|
|
ts->ts_runtime /= ratio;
|
|
ts->ts_slptime /= ratio;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Called from proc0_init() to setup the scheduler fields.
|
|
*/
|
|
void
|
|
schedinit(void)
|
|
{
|
|
struct td_sched *ts0;
|
|
|
|
/*
|
|
* Set up the scheduler specific parts of thread0.
|
|
*/
|
|
ts0 = td_get_sched(&thread0);
|
|
ts0->ts_ltick = ticks;
|
|
ts0->ts_ftick = ticks;
|
|
ts0->ts_slice = 0;
|
|
ts0->ts_cpu = curcpu; /* set valid CPU number */
|
|
}
|
|
|
|
/*
|
|
* schedinit_ap() is needed prior to calling sched_throw(NULL) to ensure that
|
|
* the pcpu requirements are met for any calls in the period between curthread
|
|
* initialization and sched_throw(). One can safely add threads to the queue
|
|
* before sched_throw(), for instance, as long as the thread lock is setup
|
|
* correctly.
|
|
*
|
|
* TDQ_SELF() relies on the below sched pcpu setting; it may be used only
|
|
* after schedinit_ap().
|
|
*/
|
|
void
|
|
schedinit_ap(void)
|
|
{
|
|
|
|
#ifdef SMP
|
|
PCPU_SET(sched, DPCPU_PTR(tdq));
|
|
#endif
|
|
PCPU_GET(idlethread)->td_lock = TDQ_LOCKPTR(TDQ_SELF());
|
|
}
|
|
|
|
/*
|
|
* This is only somewhat accurate since given many processes of the same
|
|
* priority they will switch when their slices run out, which will be
|
|
* at most sched_slice stathz ticks.
|
|
*/
|
|
int
|
|
sched_rr_interval(void)
|
|
{
|
|
|
|
/* Convert sched_slice from stathz to hz. */
|
|
return (imax(1, (sched_slice * hz + realstathz / 2) / realstathz));
|
|
}
|
|
|
|
/*
|
|
* Update the percent cpu tracking information when it is requested or
|
|
* the total history exceeds the maximum. We keep a sliding history of
|
|
* tick counts that slowly decays. This is less precise than the 4BSD
|
|
* mechanism since it happens with less regular and frequent events.
|
|
*/
|
|
static void
|
|
sched_pctcpu_update(struct td_sched *ts, int run)
|
|
{
|
|
int t = ticks;
|
|
|
|
/*
|
|
* The signed difference may be negative if the thread hasn't run for
|
|
* over half of the ticks rollover period.
|
|
*/
|
|
if ((u_int)(t - ts->ts_ltick) >= SCHED_TICK_TARG) {
|
|
ts->ts_ticks = 0;
|
|
ts->ts_ftick = t - SCHED_TICK_TARG;
|
|
} else if (t - ts->ts_ftick >= SCHED_TICK_MAX) {
|
|
ts->ts_ticks = (ts->ts_ticks / (ts->ts_ltick - ts->ts_ftick)) *
|
|
(ts->ts_ltick - (t - SCHED_TICK_TARG));
|
|
ts->ts_ftick = t - SCHED_TICK_TARG;
|
|
}
|
|
if (run)
|
|
ts->ts_ticks += (t - ts->ts_ltick) << SCHED_TICK_SHIFT;
|
|
ts->ts_ltick = t;
|
|
}
|
|
|
|
/*
|
|
* Adjust the priority of a thread. Move it to the appropriate run-queue
|
|
* if necessary. This is the back-end for several priority related
|
|
* functions.
|
|
*/
|
|
static void
|
|
sched_thread_priority(struct thread *td, u_char prio)
|
|
{
|
|
struct tdq *tdq;
|
|
int oldpri;
|
|
|
|
KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "prio",
|
|
"prio:%d", td->td_priority, "new prio:%d", prio,
|
|
KTR_ATTR_LINKED, sched_tdname(curthread));
|
|
SDT_PROBE3(sched, , , change__pri, td, td->td_proc, prio);
|
|
if (td != curthread && prio < td->td_priority) {
|
|
KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
|
|
"lend prio", "prio:%d", td->td_priority, "new prio:%d",
|
|
prio, KTR_ATTR_LINKED, sched_tdname(td));
|
|
SDT_PROBE4(sched, , , lend__pri, td, td->td_proc, prio,
|
|
curthread);
|
|
}
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
if (td->td_priority == prio)
|
|
return;
|
|
/*
|
|
* If the priority has been elevated due to priority
|
|
* propagation, we may have to move ourselves to a new
|
|
* queue. This could be optimized to not re-add in some
|
|
* cases.
|
|
*/
|
|
if (TD_ON_RUNQ(td) && prio < td->td_priority) {
|
|
sched_rem(td);
|
|
td->td_priority = prio;
|
|
sched_add(td, SRQ_BORROWING | SRQ_HOLDTD);
|
|
return;
|
|
}
|
|
/*
|
|
* If the thread is currently running we may have to adjust the lowpri
|
|
* information so other cpus are aware of our current priority.
|
|
*/
|
|
if (TD_IS_RUNNING(td)) {
|
|
tdq = TDQ_CPU(td_get_sched(td)->ts_cpu);
|
|
oldpri = td->td_priority;
|
|
td->td_priority = prio;
|
|
if (prio < tdq->tdq_lowpri)
|
|
tdq->tdq_lowpri = prio;
|
|
else if (tdq->tdq_lowpri == oldpri)
|
|
tdq_setlowpri(tdq, td);
|
|
return;
|
|
}
|
|
td->td_priority = prio;
|
|
}
|
|
|
|
/*
|
|
* Update a thread's priority when it is lent another thread's
|
|
* priority.
|
|
*/
|
|
void
|
|
sched_lend_prio(struct thread *td, u_char prio)
|
|
{
|
|
|
|
td->td_flags |= TDF_BORROWING;
|
|
sched_thread_priority(td, prio);
|
|
}
|
|
|
|
/*
|
|
* Restore a thread's priority when priority propagation is
|
|
* over. The prio argument is the minimum priority the thread
|
|
* needs to have to satisfy other possible priority lending
|
|
* requests. If the thread's regular priority is less
|
|
* important than prio, the thread will keep a priority boost
|
|
* of prio.
|
|
*/
|
|
void
|
|
sched_unlend_prio(struct thread *td, u_char prio)
|
|
{
|
|
u_char base_pri;
|
|
|
|
if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
|
|
td->td_base_pri <= PRI_MAX_TIMESHARE)
|
|
base_pri = td->td_user_pri;
|
|
else
|
|
base_pri = td->td_base_pri;
|
|
if (prio >= base_pri) {
|
|
td->td_flags &= ~TDF_BORROWING;
|
|
sched_thread_priority(td, base_pri);
|
|
} else
|
|
sched_lend_prio(td, prio);
|
|
}
|
|
|
|
/*
|
|
* Standard entry for setting the priority to an absolute value.
|
|
*/
|
|
void
|
|
sched_prio(struct thread *td, u_char prio)
|
|
{
|
|
u_char oldprio;
|
|
|
|
/* First, update the base priority. */
|
|
td->td_base_pri = prio;
|
|
|
|
/*
|
|
* If the thread is borrowing another thread's priority, don't
|
|
* ever lower the priority.
|
|
*/
|
|
if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
|
|
return;
|
|
|
|
/* Change the real priority. */
|
|
oldprio = td->td_priority;
|
|
sched_thread_priority(td, prio);
|
|
|
|
/*
|
|
* If the thread is on a turnstile, then let the turnstile update
|
|
* its state.
|
|
*/
|
|
if (TD_ON_LOCK(td) && oldprio != prio)
|
|
turnstile_adjust(td, oldprio);
|
|
}
|
|
|
|
/*
|
|
* Set the base interrupt thread priority.
|
|
*/
|
|
void
|
|
sched_ithread_prio(struct thread *td, u_char prio)
|
|
{
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
MPASS(td->td_pri_class == PRI_ITHD);
|
|
td->td_base_ithread_pri = prio;
|
|
sched_prio(td, prio);
|
|
}
|
|
|
|
/*
|
|
* Set the base user priority, does not effect current running priority.
|
|
*/
|
|
void
|
|
sched_user_prio(struct thread *td, u_char prio)
|
|
{
|
|
|
|
td->td_base_user_pri = prio;
|
|
if (td->td_lend_user_pri <= prio)
|
|
return;
|
|
td->td_user_pri = prio;
|
|
}
|
|
|
|
void
|
|
sched_lend_user_prio(struct thread *td, u_char prio)
|
|
{
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
td->td_lend_user_pri = prio;
|
|
td->td_user_pri = min(prio, td->td_base_user_pri);
|
|
if (td->td_priority > td->td_user_pri)
|
|
sched_prio(td, td->td_user_pri);
|
|
else if (td->td_priority != td->td_user_pri)
|
|
ast_sched_locked(td, TDA_SCHED);
|
|
}
|
|
|
|
/*
|
|
* Like the above but first check if there is anything to do.
|
|
*/
|
|
void
|
|
sched_lend_user_prio_cond(struct thread *td, u_char prio)
|
|
{
|
|
|
|
if (td->td_lend_user_pri == prio)
|
|
return;
|
|
|
|
thread_lock(td);
|
|
sched_lend_user_prio(td, prio);
|
|
thread_unlock(td);
|
|
}
|
|
|
|
#ifdef SMP
|
|
/*
|
|
* This tdq is about to idle. Try to steal a thread from another CPU before
|
|
* choosing the idle thread.
|
|
*/
|
|
static void
|
|
tdq_trysteal(struct tdq *tdq)
|
|
{
|
|
struct cpu_group *cg, *parent;
|
|
struct tdq *steal;
|
|
cpuset_t mask;
|
|
int cpu, i, goup;
|
|
|
|
if (smp_started == 0 || steal_idle == 0 || trysteal_limit == 0 ||
|
|
tdq->tdq_cg == NULL)
|
|
return;
|
|
CPU_FILL(&mask);
|
|
CPU_CLR(PCPU_GET(cpuid), &mask);
|
|
/* We don't want to be preempted while we're iterating. */
|
|
spinlock_enter();
|
|
TDQ_UNLOCK(tdq);
|
|
for (i = 1, cg = tdq->tdq_cg, goup = 0; ; ) {
|
|
cpu = sched_highest(cg, &mask, steal_thresh, 1);
|
|
/*
|
|
* If a thread was added while interrupts were disabled don't
|
|
* steal one here.
|
|
*/
|
|
if (TDQ_LOAD(tdq) > 0) {
|
|
TDQ_LOCK(tdq);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* We found no CPU to steal from in this group. Escalate to
|
|
* the parent and repeat. But if parent has only two children
|
|
* groups we can avoid searching this group again by searching
|
|
* the other one specifically and then escalating two levels.
|
|
*/
|
|
if (cpu == -1) {
|
|
if (goup) {
|
|
cg = cg->cg_parent;
|
|
goup = 0;
|
|
}
|
|
if (++i > trysteal_limit) {
|
|
TDQ_LOCK(tdq);
|
|
break;
|
|
}
|
|
parent = cg->cg_parent;
|
|
if (parent == NULL) {
|
|
TDQ_LOCK(tdq);
|
|
break;
|
|
}
|
|
if (parent->cg_children == 2) {
|
|
if (cg == &parent->cg_child[0])
|
|
cg = &parent->cg_child[1];
|
|
else
|
|
cg = &parent->cg_child[0];
|
|
goup = 1;
|
|
} else
|
|
cg = parent;
|
|
continue;
|
|
}
|
|
steal = TDQ_CPU(cpu);
|
|
/*
|
|
* The data returned by sched_highest() is stale and
|
|
* the chosen CPU no longer has an eligible thread.
|
|
* At this point unconditionally exit the loop to bound
|
|
* the time spent in the critcal section.
|
|
*/
|
|
if (TDQ_LOAD(steal) < steal_thresh ||
|
|
TDQ_TRANSFERABLE(steal) == 0)
|
|
continue;
|
|
/*
|
|
* Try to lock both queues. If we are assigned a thread while
|
|
* waited for the lock, switch to it now instead of stealing.
|
|
* If we can't get the lock, then somebody likely got there
|
|
* first.
|
|
*/
|
|
TDQ_LOCK(tdq);
|
|
if (tdq->tdq_load > 0)
|
|
break;
|
|
if (TDQ_TRYLOCK_FLAGS(steal, MTX_DUPOK) == 0)
|
|
break;
|
|
/*
|
|
* The data returned by sched_highest() is stale and
|
|
* the chosen CPU no longer has an eligible thread.
|
|
*/
|
|
if (TDQ_LOAD(steal) < steal_thresh ||
|
|
TDQ_TRANSFERABLE(steal) == 0) {
|
|
TDQ_UNLOCK(steal);
|
|
break;
|
|
}
|
|
/*
|
|
* If we fail to acquire one due to affinity restrictions,
|
|
* bail out and let the idle thread to a more complete search
|
|
* outside of a critical section.
|
|
*/
|
|
if (tdq_move(steal, tdq) == -1) {
|
|
TDQ_UNLOCK(steal);
|
|
break;
|
|
}
|
|
TDQ_UNLOCK(steal);
|
|
break;
|
|
}
|
|
spinlock_exit();
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Handle migration from sched_switch(). This happens only for
|
|
* cpu binding.
|
|
*/
|
|
static struct mtx *
|
|
sched_switch_migrate(struct tdq *tdq, struct thread *td, int flags)
|
|
{
|
|
struct tdq *tdn;
|
|
#ifdef SMP
|
|
int lowpri;
|
|
#endif
|
|
|
|
KASSERT(THREAD_CAN_MIGRATE(td) ||
|
|
(td_get_sched(td)->ts_flags & TSF_BOUND) != 0,
|
|
("Thread %p shouldn't migrate", td));
|
|
KASSERT(!CPU_ABSENT(td_get_sched(td)->ts_cpu), ("sched_switch_migrate: "
|
|
"thread %s queued on absent CPU %d.", td->td_name,
|
|
td_get_sched(td)->ts_cpu));
|
|
tdn = TDQ_CPU(td_get_sched(td)->ts_cpu);
|
|
#ifdef SMP
|
|
tdq_load_rem(tdq, td);
|
|
/*
|
|
* Do the lock dance required to avoid LOR. We have an
|
|
* extra spinlock nesting from sched_switch() which will
|
|
* prevent preemption while we're holding neither run-queue lock.
|
|
*/
|
|
TDQ_UNLOCK(tdq);
|
|
TDQ_LOCK(tdn);
|
|
lowpri = tdq_add(tdn, td, flags);
|
|
tdq_notify(tdn, lowpri);
|
|
TDQ_UNLOCK(tdn);
|
|
TDQ_LOCK(tdq);
|
|
#endif
|
|
return (TDQ_LOCKPTR(tdn));
|
|
}
|
|
|
|
/*
|
|
* thread_lock_unblock() that does not assume td_lock is blocked.
|
|
*/
|
|
static inline void
|
|
thread_unblock_switch(struct thread *td, struct mtx *mtx)
|
|
{
|
|
atomic_store_rel_ptr((volatile uintptr_t *)&td->td_lock,
|
|
(uintptr_t)mtx);
|
|
}
|
|
|
|
/*
|
|
* Switch threads. This function has to handle threads coming in while
|
|
* blocked for some reason, running, or idle. It also must deal with
|
|
* migrating a thread from one queue to another as running threads may
|
|
* be assigned elsewhere via binding.
|
|
*/
|
|
void
|
|
sched_switch(struct thread *td, int flags)
|
|
{
|
|
struct thread *newtd;
|
|
struct tdq *tdq;
|
|
struct td_sched *ts;
|
|
struct mtx *mtx;
|
|
int srqflag;
|
|
int cpuid, preempted;
|
|
#ifdef SMP
|
|
int pickcpu;
|
|
#endif
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
|
|
cpuid = PCPU_GET(cpuid);
|
|
tdq = TDQ_SELF();
|
|
ts = td_get_sched(td);
|
|
sched_pctcpu_update(ts, 1);
|
|
#ifdef SMP
|
|
pickcpu = (td->td_flags & TDF_PICKCPU) != 0;
|
|
if (pickcpu)
|
|
ts->ts_rltick = ticks - affinity * MAX_CACHE_LEVELS;
|
|
else
|
|
ts->ts_rltick = ticks;
|
|
#endif
|
|
td->td_lastcpu = td->td_oncpu;
|
|
preempted = (td->td_flags & TDF_SLICEEND) == 0 &&
|
|
(flags & SW_PREEMPT) != 0;
|
|
td->td_flags &= ~(TDF_PICKCPU | TDF_SLICEEND);
|
|
ast_unsched_locked(td, TDA_SCHED);
|
|
td->td_owepreempt = 0;
|
|
atomic_store_char(&tdq->tdq_owepreempt, 0);
|
|
if (!TD_IS_IDLETHREAD(td))
|
|
TDQ_SWITCHCNT_INC(tdq);
|
|
|
|
/*
|
|
* Always block the thread lock so we can drop the tdq lock early.
|
|
*/
|
|
mtx = thread_lock_block(td);
|
|
spinlock_enter();
|
|
if (TD_IS_IDLETHREAD(td)) {
|
|
MPASS(mtx == TDQ_LOCKPTR(tdq));
|
|
TD_SET_CAN_RUN(td);
|
|
} else if (TD_IS_RUNNING(td)) {
|
|
MPASS(mtx == TDQ_LOCKPTR(tdq));
|
|
srqflag = SRQ_OURSELF | SRQ_YIELDING |
|
|
(preempted ? SRQ_PREEMPTED : 0);
|
|
#ifdef SMP
|
|
if (THREAD_CAN_MIGRATE(td) && (!THREAD_CAN_SCHED(td, ts->ts_cpu)
|
|
|| pickcpu))
|
|
ts->ts_cpu = sched_pickcpu(td, 0);
|
|
#endif
|
|
if (ts->ts_cpu == cpuid)
|
|
tdq_runq_add(tdq, td, srqflag);
|
|
else
|
|
mtx = sched_switch_migrate(tdq, td, srqflag);
|
|
} else {
|
|
/* This thread must be going to sleep. */
|
|
if (mtx != TDQ_LOCKPTR(tdq)) {
|
|
mtx_unlock_spin(mtx);
|
|
TDQ_LOCK(tdq);
|
|
}
|
|
tdq_load_rem(tdq, td);
|
|
#ifdef SMP
|
|
if (tdq->tdq_load == 0)
|
|
tdq_trysteal(tdq);
|
|
#endif
|
|
}
|
|
|
|
#if (KTR_COMPILE & KTR_SCHED) != 0
|
|
if (TD_IS_IDLETHREAD(td))
|
|
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "idle",
|
|
"prio:%d", td->td_priority);
|
|
else
|
|
KTR_STATE3(KTR_SCHED, "thread", sched_tdname(td), KTDSTATE(td),
|
|
"prio:%d", td->td_priority, "wmesg:\"%s\"", td->td_wmesg,
|
|
"lockname:\"%s\"", td->td_lockname);
|
|
#endif
|
|
|
|
/*
|
|
* We enter here with the thread blocked and assigned to the
|
|
* appropriate cpu run-queue or sleep-queue and with the current
|
|
* thread-queue locked.
|
|
*/
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED | MA_NOTRECURSED);
|
|
MPASS(td == tdq->tdq_curthread);
|
|
newtd = choosethread();
|
|
sched_pctcpu_update(td_get_sched(newtd), 0);
|
|
TDQ_UNLOCK(tdq);
|
|
|
|
/*
|
|
* Call the MD code to switch contexts if necessary.
|
|
*/
|
|
if (td != newtd) {
|
|
#ifdef HWPMC_HOOKS
|
|
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
|
|
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_OUT);
|
|
#endif
|
|
SDT_PROBE2(sched, , , off__cpu, newtd, newtd->td_proc);
|
|
|
|
#ifdef KDTRACE_HOOKS
|
|
/*
|
|
* If DTrace has set the active vtime enum to anything
|
|
* other than INACTIVE (0), then it should have set the
|
|
* function to call.
|
|
*/
|
|
if (dtrace_vtime_active)
|
|
(*dtrace_vtime_switch_func)(newtd);
|
|
#endif
|
|
td->td_oncpu = NOCPU;
|
|
cpu_switch(td, newtd, mtx);
|
|
cpuid = td->td_oncpu = PCPU_GET(cpuid);
|
|
|
|
SDT_PROBE0(sched, , , on__cpu);
|
|
#ifdef HWPMC_HOOKS
|
|
if (PMC_PROC_IS_USING_PMCS(td->td_proc))
|
|
PMC_SWITCH_CONTEXT(td, PMC_FN_CSW_IN);
|
|
#endif
|
|
} else {
|
|
thread_unblock_switch(td, mtx);
|
|
SDT_PROBE0(sched, , , remain__cpu);
|
|
}
|
|
KASSERT(curthread->td_md.md_spinlock_count == 1,
|
|
("invalid count %d", curthread->td_md.md_spinlock_count));
|
|
|
|
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
|
|
"prio:%d", td->td_priority);
|
|
}
|
|
|
|
/*
|
|
* Adjust thread priorities as a result of a nice request.
|
|
*/
|
|
void
|
|
sched_nice(struct proc *p, int nice)
|
|
{
|
|
struct thread *td;
|
|
|
|
PROC_LOCK_ASSERT(p, MA_OWNED);
|
|
|
|
p->p_nice = nice;
|
|
FOREACH_THREAD_IN_PROC(p, td) {
|
|
thread_lock(td);
|
|
sched_priority(td);
|
|
sched_prio(td, td->td_base_user_pri);
|
|
thread_unlock(td);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Record the sleep time for the interactivity scorer.
|
|
*/
|
|
void
|
|
sched_sleep(struct thread *td, int prio)
|
|
{
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
|
|
td->td_slptick = ticks;
|
|
if (TD_IS_SUSPENDED(td) || prio >= PSOCK)
|
|
td->td_flags |= TDF_CANSWAP;
|
|
if (PRI_BASE(td->td_pri_class) != PRI_TIMESHARE)
|
|
return;
|
|
if (static_boost == 1 && prio)
|
|
sched_prio(td, prio);
|
|
else if (static_boost && td->td_priority > static_boost)
|
|
sched_prio(td, static_boost);
|
|
}
|
|
|
|
/*
|
|
* Schedule a thread to resume execution and record how long it voluntarily
|
|
* slept. We also update the pctcpu, interactivity, and priority.
|
|
*
|
|
* Requires the thread lock on entry, drops on exit.
|
|
*/
|
|
void
|
|
sched_wakeup(struct thread *td, int srqflags)
|
|
{
|
|
struct td_sched *ts;
|
|
int slptick;
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
ts = td_get_sched(td);
|
|
td->td_flags &= ~TDF_CANSWAP;
|
|
|
|
/*
|
|
* If we slept for more than a tick update our interactivity and
|
|
* priority.
|
|
*/
|
|
slptick = td->td_slptick;
|
|
td->td_slptick = 0;
|
|
if (slptick && slptick != ticks) {
|
|
ts->ts_slptime += (ticks - slptick) << SCHED_TICK_SHIFT;
|
|
sched_interact_update(td);
|
|
sched_pctcpu_update(ts, 0);
|
|
}
|
|
|
|
/*
|
|
* When resuming an idle ithread, restore its base ithread
|
|
* priority.
|
|
*/
|
|
if (PRI_BASE(td->td_pri_class) == PRI_ITHD &&
|
|
td->td_priority != td->td_base_ithread_pri)
|
|
sched_prio(td, td->td_base_ithread_pri);
|
|
|
|
/*
|
|
* Reset the slice value since we slept and advanced the round-robin.
|
|
*/
|
|
ts->ts_slice = 0;
|
|
sched_add(td, SRQ_BORING | srqflags);
|
|
}
|
|
|
|
/*
|
|
* Penalize the parent for creating a new child and initialize the child's
|
|
* priority.
|
|
*/
|
|
void
|
|
sched_fork(struct thread *td, struct thread *child)
|
|
{
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
sched_pctcpu_update(td_get_sched(td), 1);
|
|
sched_fork_thread(td, child);
|
|
/*
|
|
* Penalize the parent and child for forking.
|
|
*/
|
|
sched_interact_fork(child);
|
|
sched_priority(child);
|
|
td_get_sched(td)->ts_runtime += tickincr;
|
|
sched_interact_update(td);
|
|
sched_priority(td);
|
|
}
|
|
|
|
/*
|
|
* Fork a new thread, may be within the same process.
|
|
*/
|
|
void
|
|
sched_fork_thread(struct thread *td, struct thread *child)
|
|
{
|
|
struct td_sched *ts;
|
|
struct td_sched *ts2;
|
|
struct tdq *tdq;
|
|
|
|
tdq = TDQ_SELF();
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
/*
|
|
* Initialize child.
|
|
*/
|
|
ts = td_get_sched(td);
|
|
ts2 = td_get_sched(child);
|
|
child->td_oncpu = NOCPU;
|
|
child->td_lastcpu = NOCPU;
|
|
child->td_lock = TDQ_LOCKPTR(tdq);
|
|
child->td_cpuset = cpuset_ref(td->td_cpuset);
|
|
child->td_domain.dr_policy = td->td_cpuset->cs_domain;
|
|
ts2->ts_cpu = ts->ts_cpu;
|
|
ts2->ts_flags = 0;
|
|
/*
|
|
* Grab our parents cpu estimation information.
|
|
*/
|
|
ts2->ts_ticks = ts->ts_ticks;
|
|
ts2->ts_ltick = ts->ts_ltick;
|
|
ts2->ts_ftick = ts->ts_ftick;
|
|
/*
|
|
* Do not inherit any borrowed priority from the parent.
|
|
*/
|
|
child->td_priority = child->td_base_pri;
|
|
/*
|
|
* And update interactivity score.
|
|
*/
|
|
ts2->ts_slptime = ts->ts_slptime;
|
|
ts2->ts_runtime = ts->ts_runtime;
|
|
/* Attempt to quickly learn interactivity. */
|
|
ts2->ts_slice = tdq_slice(tdq) - sched_slice_min;
|
|
#ifdef KTR
|
|
bzero(ts2->ts_name, sizeof(ts2->ts_name));
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Adjust the priority class of a thread.
|
|
*/
|
|
void
|
|
sched_class(struct thread *td, int class)
|
|
{
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
if (td->td_pri_class == class)
|
|
return;
|
|
td->td_pri_class = class;
|
|
}
|
|
|
|
/*
|
|
* Return some of the child's priority and interactivity to the parent.
|
|
*/
|
|
void
|
|
sched_exit(struct proc *p, struct thread *child)
|
|
{
|
|
struct thread *td;
|
|
|
|
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "proc exit",
|
|
"prio:%d", child->td_priority);
|
|
PROC_LOCK_ASSERT(p, MA_OWNED);
|
|
td = FIRST_THREAD_IN_PROC(p);
|
|
sched_exit_thread(td, child);
|
|
}
|
|
|
|
/*
|
|
* Penalize another thread for the time spent on this one. This helps to
|
|
* worsen the priority and interactivity of processes which schedule batch
|
|
* jobs such as make. This has little effect on the make process itself but
|
|
* causes new processes spawned by it to receive worse scores immediately.
|
|
*/
|
|
void
|
|
sched_exit_thread(struct thread *td, struct thread *child)
|
|
{
|
|
|
|
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "thread exit",
|
|
"prio:%d", child->td_priority);
|
|
/*
|
|
* Give the child's runtime to the parent without returning the
|
|
* sleep time as a penalty to the parent. This causes shells that
|
|
* launch expensive things to mark their children as expensive.
|
|
*/
|
|
thread_lock(td);
|
|
td_get_sched(td)->ts_runtime += td_get_sched(child)->ts_runtime;
|
|
sched_interact_update(td);
|
|
sched_priority(td);
|
|
thread_unlock(td);
|
|
}
|
|
|
|
void
|
|
sched_preempt(struct thread *td)
|
|
{
|
|
struct tdq *tdq;
|
|
int flags;
|
|
|
|
SDT_PROBE2(sched, , , surrender, td, td->td_proc);
|
|
|
|
thread_lock(td);
|
|
tdq = TDQ_SELF();
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
if (td->td_priority > tdq->tdq_lowpri) {
|
|
if (td->td_critnest == 1) {
|
|
flags = SW_INVOL | SW_PREEMPT;
|
|
flags |= TD_IS_IDLETHREAD(td) ? SWT_REMOTEWAKEIDLE :
|
|
SWT_REMOTEPREEMPT;
|
|
mi_switch(flags);
|
|
/* Switch dropped thread lock. */
|
|
return;
|
|
}
|
|
td->td_owepreempt = 1;
|
|
} else {
|
|
tdq->tdq_owepreempt = 0;
|
|
}
|
|
thread_unlock(td);
|
|
}
|
|
|
|
/*
|
|
* Fix priorities on return to user-space. Priorities may be elevated due
|
|
* to static priorities in msleep() or similar.
|
|
*/
|
|
void
|
|
sched_userret_slowpath(struct thread *td)
|
|
{
|
|
|
|
thread_lock(td);
|
|
td->td_priority = td->td_user_pri;
|
|
td->td_base_pri = td->td_user_pri;
|
|
tdq_setlowpri(TDQ_SELF(), td);
|
|
thread_unlock(td);
|
|
}
|
|
|
|
SCHED_STAT_DEFINE(ithread_demotions, "Interrupt thread priority demotions");
|
|
SCHED_STAT_DEFINE(ithread_preemptions,
|
|
"Interrupt thread preemptions due to time-sharing");
|
|
|
|
/*
|
|
* Return time slice for a given thread. For ithreads this is
|
|
* sched_slice. For other threads it is tdq_slice(tdq).
|
|
*/
|
|
static inline int
|
|
td_slice(struct thread *td, struct tdq *tdq)
|
|
{
|
|
if (PRI_BASE(td->td_pri_class) == PRI_ITHD)
|
|
return (sched_slice);
|
|
return (tdq_slice(tdq));
|
|
}
|
|
|
|
/*
|
|
* Handle a stathz tick. This is really only relevant for timeshare
|
|
* and interrupt threads.
|
|
*/
|
|
void
|
|
sched_clock(struct thread *td, int cnt)
|
|
{
|
|
struct tdq *tdq;
|
|
struct td_sched *ts;
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
tdq = TDQ_SELF();
|
|
#ifdef SMP
|
|
/*
|
|
* We run the long term load balancer infrequently on the first cpu.
|
|
*/
|
|
if (balance_tdq == tdq && smp_started != 0 && rebalance != 0 &&
|
|
balance_ticks != 0) {
|
|
balance_ticks -= cnt;
|
|
if (balance_ticks <= 0)
|
|
sched_balance();
|
|
}
|
|
#endif
|
|
/*
|
|
* Save the old switch count so we have a record of the last ticks
|
|
* activity. Initialize the new switch count based on our load.
|
|
* If there is some activity seed it to reflect that.
|
|
*/
|
|
tdq->tdq_oldswitchcnt = tdq->tdq_switchcnt;
|
|
tdq->tdq_switchcnt = tdq->tdq_load;
|
|
|
|
/*
|
|
* Advance the insert index once for each tick to ensure that all
|
|
* threads get a chance to run.
|
|
*/
|
|
if (tdq->tdq_idx == tdq->tdq_ridx) {
|
|
tdq->tdq_idx = (tdq->tdq_idx + 1) % RQ_NQS;
|
|
if (TAILQ_EMPTY(&tdq->tdq_timeshare.rq_queues[tdq->tdq_ridx]))
|
|
tdq->tdq_ridx = tdq->tdq_idx;
|
|
}
|
|
ts = td_get_sched(td);
|
|
sched_pctcpu_update(ts, 1);
|
|
if ((td->td_pri_class & PRI_FIFO_BIT) || TD_IS_IDLETHREAD(td))
|
|
return;
|
|
|
|
if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE) {
|
|
/*
|
|
* We used a tick; charge it to the thread so
|
|
* that we can compute our interactivity.
|
|
*/
|
|
td_get_sched(td)->ts_runtime += tickincr * cnt;
|
|
sched_interact_update(td);
|
|
sched_priority(td);
|
|
}
|
|
|
|
/*
|
|
* Force a context switch if the current thread has used up a full
|
|
* time slice (default is 100ms).
|
|
*/
|
|
ts->ts_slice += cnt;
|
|
if (ts->ts_slice >= td_slice(td, tdq)) {
|
|
ts->ts_slice = 0;
|
|
|
|
/*
|
|
* If an ithread uses a full quantum, demote its
|
|
* priority and preempt it.
|
|
*/
|
|
if (PRI_BASE(td->td_pri_class) == PRI_ITHD) {
|
|
SCHED_STAT_INC(ithread_preemptions);
|
|
td->td_owepreempt = 1;
|
|
if (td->td_base_pri + RQ_PPQ < PRI_MAX_ITHD) {
|
|
SCHED_STAT_INC(ithread_demotions);
|
|
sched_prio(td, td->td_base_pri + RQ_PPQ);
|
|
}
|
|
} else {
|
|
ast_sched_locked(td, TDA_SCHED);
|
|
td->td_flags |= TDF_SLICEEND;
|
|
}
|
|
}
|
|
}
|
|
|
|
u_int
|
|
sched_estcpu(struct thread *td __unused)
|
|
{
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Return whether the current CPU has runnable tasks. Used for in-kernel
|
|
* cooperative idle threads.
|
|
*/
|
|
int
|
|
sched_runnable(void)
|
|
{
|
|
struct tdq *tdq;
|
|
int load;
|
|
|
|
load = 1;
|
|
|
|
tdq = TDQ_SELF();
|
|
if ((curthread->td_flags & TDF_IDLETD) != 0) {
|
|
if (TDQ_LOAD(tdq) > 0)
|
|
goto out;
|
|
} else
|
|
if (TDQ_LOAD(tdq) - 1 > 0)
|
|
goto out;
|
|
load = 0;
|
|
out:
|
|
return (load);
|
|
}
|
|
|
|
/*
|
|
* Choose the highest priority thread to run. The thread is removed from
|
|
* the run-queue while running however the load remains.
|
|
*/
|
|
struct thread *
|
|
sched_choose(void)
|
|
{
|
|
struct thread *td;
|
|
struct tdq *tdq;
|
|
|
|
tdq = TDQ_SELF();
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
td = tdq_choose(tdq);
|
|
if (td != NULL) {
|
|
tdq_runq_rem(tdq, td);
|
|
tdq->tdq_lowpri = td->td_priority;
|
|
} else {
|
|
tdq->tdq_lowpri = PRI_MAX_IDLE;
|
|
td = PCPU_GET(idlethread);
|
|
}
|
|
tdq->tdq_curthread = td;
|
|
return (td);
|
|
}
|
|
|
|
/*
|
|
* Set owepreempt if the currently running thread has lower priority than "pri".
|
|
* Preemption never happens directly in ULE, we always request it once we exit a
|
|
* critical section.
|
|
*/
|
|
static void
|
|
sched_setpreempt(int pri)
|
|
{
|
|
struct thread *ctd;
|
|
int cpri;
|
|
|
|
ctd = curthread;
|
|
THREAD_LOCK_ASSERT(ctd, MA_OWNED);
|
|
|
|
cpri = ctd->td_priority;
|
|
if (pri < cpri)
|
|
ast_sched_locked(ctd, TDA_SCHED);
|
|
if (KERNEL_PANICKED() || pri >= cpri || cold || TD_IS_INHIBITED(ctd))
|
|
return;
|
|
if (!sched_shouldpreempt(pri, cpri, 0))
|
|
return;
|
|
ctd->td_owepreempt = 1;
|
|
}
|
|
|
|
/*
|
|
* Add a thread to a thread queue. Select the appropriate runq and add the
|
|
* thread to it. This is the internal function called when the tdq is
|
|
* predetermined.
|
|
*/
|
|
static int
|
|
tdq_add(struct tdq *tdq, struct thread *td, int flags)
|
|
{
|
|
int lowpri;
|
|
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
THREAD_LOCK_BLOCKED_ASSERT(td, MA_OWNED);
|
|
KASSERT((td->td_inhibitors == 0),
|
|
("sched_add: trying to run inhibited thread"));
|
|
KASSERT((TD_CAN_RUN(td) || TD_IS_RUNNING(td)),
|
|
("sched_add: bad thread state"));
|
|
KASSERT(td->td_flags & TDF_INMEM,
|
|
("sched_add: thread swapped out"));
|
|
|
|
lowpri = tdq->tdq_lowpri;
|
|
if (td->td_priority < lowpri)
|
|
tdq->tdq_lowpri = td->td_priority;
|
|
tdq_runq_add(tdq, td, flags);
|
|
tdq_load_add(tdq, td);
|
|
return (lowpri);
|
|
}
|
|
|
|
/*
|
|
* Select the target thread queue and add a thread to it. Request
|
|
* preemption or IPI a remote processor if required.
|
|
*
|
|
* Requires the thread lock on entry, drops on exit.
|
|
*/
|
|
void
|
|
sched_add(struct thread *td, int flags)
|
|
{
|
|
struct tdq *tdq;
|
|
#ifdef SMP
|
|
int cpu, lowpri;
|
|
#endif
|
|
|
|
KTR_STATE2(KTR_SCHED, "thread", sched_tdname(td), "runq add",
|
|
"prio:%d", td->td_priority, KTR_ATTR_LINKED,
|
|
sched_tdname(curthread));
|
|
KTR_POINT1(KTR_SCHED, "thread", sched_tdname(curthread), "wokeup",
|
|
KTR_ATTR_LINKED, sched_tdname(td));
|
|
SDT_PROBE4(sched, , , enqueue, td, td->td_proc, NULL,
|
|
flags & SRQ_PREEMPTED);
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
/*
|
|
* Recalculate the priority before we select the target cpu or
|
|
* run-queue.
|
|
*/
|
|
if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
|
|
sched_priority(td);
|
|
#ifdef SMP
|
|
/*
|
|
* Pick the destination cpu and if it isn't ours transfer to the
|
|
* target cpu.
|
|
*/
|
|
cpu = sched_pickcpu(td, flags);
|
|
tdq = sched_setcpu(td, cpu, flags);
|
|
lowpri = tdq_add(tdq, td, flags);
|
|
if (cpu != PCPU_GET(cpuid))
|
|
tdq_notify(tdq, lowpri);
|
|
else if (!(flags & SRQ_YIELDING))
|
|
sched_setpreempt(td->td_priority);
|
|
#else
|
|
tdq = TDQ_SELF();
|
|
/*
|
|
* Now that the thread is moving to the run-queue, set the lock
|
|
* to the scheduler's lock.
|
|
*/
|
|
if (td->td_lock != TDQ_LOCKPTR(tdq)) {
|
|
TDQ_LOCK(tdq);
|
|
if ((flags & SRQ_HOLD) != 0)
|
|
td->td_lock = TDQ_LOCKPTR(tdq);
|
|
else
|
|
thread_lock_set(td, TDQ_LOCKPTR(tdq));
|
|
}
|
|
(void)tdq_add(tdq, td, flags);
|
|
if (!(flags & SRQ_YIELDING))
|
|
sched_setpreempt(td->td_priority);
|
|
#endif
|
|
if (!(flags & SRQ_HOLDTD))
|
|
thread_unlock(td);
|
|
}
|
|
|
|
/*
|
|
* Remove a thread from a run-queue without running it. This is used
|
|
* when we're stealing a thread from a remote queue. Otherwise all threads
|
|
* exit by calling sched_exit_thread() and sched_throw() themselves.
|
|
*/
|
|
void
|
|
sched_rem(struct thread *td)
|
|
{
|
|
struct tdq *tdq;
|
|
|
|
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "runq rem",
|
|
"prio:%d", td->td_priority);
|
|
SDT_PROBE3(sched, , , dequeue, td, td->td_proc, NULL);
|
|
tdq = TDQ_CPU(td_get_sched(td)->ts_cpu);
|
|
TDQ_LOCK_ASSERT(tdq, MA_OWNED);
|
|
MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
|
|
KASSERT(TD_ON_RUNQ(td),
|
|
("sched_rem: thread not on run queue"));
|
|
tdq_runq_rem(tdq, td);
|
|
tdq_load_rem(tdq, td);
|
|
TD_SET_CAN_RUN(td);
|
|
if (td->td_priority == tdq->tdq_lowpri)
|
|
tdq_setlowpri(tdq, NULL);
|
|
}
|
|
|
|
/*
|
|
* Fetch cpu utilization information. Updates on demand.
|
|
*/
|
|
fixpt_t
|
|
sched_pctcpu(struct thread *td)
|
|
{
|
|
fixpt_t pctcpu;
|
|
struct td_sched *ts;
|
|
|
|
pctcpu = 0;
|
|
ts = td_get_sched(td);
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
sched_pctcpu_update(ts, TD_IS_RUNNING(td));
|
|
if (ts->ts_ticks) {
|
|
int rtick;
|
|
|
|
/* How many rtick per second ? */
|
|
rtick = min(SCHED_TICK_HZ(ts) / SCHED_TICK_SECS, hz);
|
|
pctcpu = (FSCALE * ((FSCALE * rtick)/hz)) >> FSHIFT;
|
|
}
|
|
|
|
return (pctcpu);
|
|
}
|
|
|
|
/*
|
|
* Enforce affinity settings for a thread. Called after adjustments to
|
|
* cpumask.
|
|
*/
|
|
void
|
|
sched_affinity(struct thread *td)
|
|
{
|
|
#ifdef SMP
|
|
struct td_sched *ts;
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
ts = td_get_sched(td);
|
|
if (THREAD_CAN_SCHED(td, ts->ts_cpu))
|
|
return;
|
|
if (TD_ON_RUNQ(td)) {
|
|
sched_rem(td);
|
|
sched_add(td, SRQ_BORING | SRQ_HOLDTD);
|
|
return;
|
|
}
|
|
if (!TD_IS_RUNNING(td))
|
|
return;
|
|
/*
|
|
* Force a switch before returning to userspace. If the
|
|
* target thread is not running locally send an ipi to force
|
|
* the issue.
|
|
*/
|
|
ast_sched_locked(td, TDA_SCHED);
|
|
if (td != curthread)
|
|
ipi_cpu(ts->ts_cpu, IPI_PREEMPT);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Bind a thread to a target cpu.
|
|
*/
|
|
void
|
|
sched_bind(struct thread *td, int cpu)
|
|
{
|
|
struct td_sched *ts;
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED|MA_NOTRECURSED);
|
|
KASSERT(td == curthread, ("sched_bind: can only bind curthread"));
|
|
ts = td_get_sched(td);
|
|
if (ts->ts_flags & TSF_BOUND)
|
|
sched_unbind(td);
|
|
KASSERT(THREAD_CAN_MIGRATE(td), ("%p must be migratable", td));
|
|
ts->ts_flags |= TSF_BOUND;
|
|
sched_pin();
|
|
if (PCPU_GET(cpuid) == cpu)
|
|
return;
|
|
ts->ts_cpu = cpu;
|
|
/* When we return from mi_switch we'll be on the correct cpu. */
|
|
mi_switch(SW_VOL | SWT_BIND);
|
|
thread_lock(td);
|
|
}
|
|
|
|
/*
|
|
* Release a bound thread.
|
|
*/
|
|
void
|
|
sched_unbind(struct thread *td)
|
|
{
|
|
struct td_sched *ts;
|
|
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
KASSERT(td == curthread, ("sched_unbind: can only bind curthread"));
|
|
ts = td_get_sched(td);
|
|
if ((ts->ts_flags & TSF_BOUND) == 0)
|
|
return;
|
|
ts->ts_flags &= ~TSF_BOUND;
|
|
sched_unpin();
|
|
}
|
|
|
|
int
|
|
sched_is_bound(struct thread *td)
|
|
{
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
return (td_get_sched(td)->ts_flags & TSF_BOUND);
|
|
}
|
|
|
|
/*
|
|
* Basic yield call.
|
|
*/
|
|
void
|
|
sched_relinquish(struct thread *td)
|
|
{
|
|
thread_lock(td);
|
|
mi_switch(SW_VOL | SWT_RELINQUISH);
|
|
}
|
|
|
|
/*
|
|
* Return the total system load.
|
|
*/
|
|
int
|
|
sched_load(void)
|
|
{
|
|
#ifdef SMP
|
|
int total;
|
|
int i;
|
|
|
|
total = 0;
|
|
CPU_FOREACH(i)
|
|
total += atomic_load_int(&TDQ_CPU(i)->tdq_sysload);
|
|
return (total);
|
|
#else
|
|
return (atomic_load_int(&TDQ_SELF()->tdq_sysload));
|
|
#endif
|
|
}
|
|
|
|
int
|
|
sched_sizeof_proc(void)
|
|
{
|
|
return (sizeof(struct proc));
|
|
}
|
|
|
|
int
|
|
sched_sizeof_thread(void)
|
|
{
|
|
return (sizeof(struct thread) + sizeof(struct td_sched));
|
|
}
|
|
|
|
#ifdef SMP
|
|
#define TDQ_IDLESPIN(tdq) \
|
|
((tdq)->tdq_cg != NULL && ((tdq)->tdq_cg->cg_flags & CG_FLAG_THREAD) == 0)
|
|
#else
|
|
#define TDQ_IDLESPIN(tdq) 1
|
|
#endif
|
|
|
|
/*
|
|
* The actual idle process.
|
|
*/
|
|
void
|
|
sched_idletd(void *dummy)
|
|
{
|
|
struct thread *td;
|
|
struct tdq *tdq;
|
|
int oldswitchcnt, switchcnt;
|
|
int i;
|
|
|
|
mtx_assert(&Giant, MA_NOTOWNED);
|
|
td = curthread;
|
|
tdq = TDQ_SELF();
|
|
THREAD_NO_SLEEPING();
|
|
oldswitchcnt = -1;
|
|
for (;;) {
|
|
if (TDQ_LOAD(tdq)) {
|
|
thread_lock(td);
|
|
mi_switch(SW_VOL | SWT_IDLE);
|
|
}
|
|
switchcnt = TDQ_SWITCHCNT(tdq);
|
|
#ifdef SMP
|
|
if (always_steal || switchcnt != oldswitchcnt) {
|
|
oldswitchcnt = switchcnt;
|
|
if (tdq_idled(tdq) == 0)
|
|
continue;
|
|
}
|
|
switchcnt = TDQ_SWITCHCNT(tdq);
|
|
#else
|
|
oldswitchcnt = switchcnt;
|
|
#endif
|
|
/*
|
|
* If we're switching very frequently, spin while checking
|
|
* for load rather than entering a low power state that
|
|
* may require an IPI. However, don't do any busy
|
|
* loops while on SMT machines as this simply steals
|
|
* cycles from cores doing useful work.
|
|
*/
|
|
if (TDQ_IDLESPIN(tdq) && switchcnt > sched_idlespinthresh) {
|
|
for (i = 0; i < sched_idlespins; i++) {
|
|
if (TDQ_LOAD(tdq))
|
|
break;
|
|
cpu_spinwait();
|
|
}
|
|
}
|
|
|
|
/* If there was context switch during spin, restart it. */
|
|
switchcnt = TDQ_SWITCHCNT(tdq);
|
|
if (TDQ_LOAD(tdq) != 0 || switchcnt != oldswitchcnt)
|
|
continue;
|
|
|
|
/* Run main MD idle handler. */
|
|
atomic_store_int(&tdq->tdq_cpu_idle, 1);
|
|
/*
|
|
* Make sure that the tdq_cpu_idle update is globally visible
|
|
* before cpu_idle() reads tdq_load. The order is important
|
|
* to avoid races with tdq_notify().
|
|
*/
|
|
atomic_thread_fence_seq_cst();
|
|
/*
|
|
* Checking for again after the fence picks up assigned
|
|
* threads often enough to make it worthwhile to do so in
|
|
* order to avoid calling cpu_idle().
|
|
*/
|
|
if (TDQ_LOAD(tdq) != 0) {
|
|
atomic_store_int(&tdq->tdq_cpu_idle, 0);
|
|
continue;
|
|
}
|
|
cpu_idle(switchcnt * 4 > sched_idlespinthresh);
|
|
atomic_store_int(&tdq->tdq_cpu_idle, 0);
|
|
|
|
/*
|
|
* Account thread-less hardware interrupts and
|
|
* other wakeup reasons equal to context switches.
|
|
*/
|
|
switchcnt = TDQ_SWITCHCNT(tdq);
|
|
if (switchcnt != oldswitchcnt)
|
|
continue;
|
|
TDQ_SWITCHCNT_INC(tdq);
|
|
oldswitchcnt++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* sched_throw_grab() chooses a thread from the queue to switch to
|
|
* next. It returns with the tdq lock dropped in a spinlock section to
|
|
* keep interrupts disabled until the CPU is running in a proper threaded
|
|
* context.
|
|
*/
|
|
static struct thread *
|
|
sched_throw_grab(struct tdq *tdq)
|
|
{
|
|
struct thread *newtd;
|
|
|
|
newtd = choosethread();
|
|
spinlock_enter();
|
|
TDQ_UNLOCK(tdq);
|
|
KASSERT(curthread->td_md.md_spinlock_count == 1,
|
|
("invalid count %d", curthread->td_md.md_spinlock_count));
|
|
return (newtd);
|
|
}
|
|
|
|
/*
|
|
* A CPU is entering for the first time.
|
|
*/
|
|
void
|
|
sched_ap_entry(void)
|
|
{
|
|
struct thread *newtd;
|
|
struct tdq *tdq;
|
|
|
|
tdq = TDQ_SELF();
|
|
|
|
/* This should have been setup in schedinit_ap(). */
|
|
THREAD_LOCKPTR_ASSERT(curthread, TDQ_LOCKPTR(tdq));
|
|
|
|
TDQ_LOCK(tdq);
|
|
/* Correct spinlock nesting. */
|
|
spinlock_exit();
|
|
PCPU_SET(switchtime, cpu_ticks());
|
|
PCPU_SET(switchticks, ticks);
|
|
|
|
newtd = sched_throw_grab(tdq);
|
|
|
|
/* doesn't return */
|
|
cpu_throw(NULL, newtd);
|
|
}
|
|
|
|
/*
|
|
* A thread is exiting.
|
|
*/
|
|
void
|
|
sched_throw(struct thread *td)
|
|
{
|
|
struct thread *newtd;
|
|
struct tdq *tdq;
|
|
|
|
tdq = TDQ_SELF();
|
|
|
|
MPASS(td != NULL);
|
|
THREAD_LOCK_ASSERT(td, MA_OWNED);
|
|
THREAD_LOCKPTR_ASSERT(td, TDQ_LOCKPTR(tdq));
|
|
|
|
tdq_load_rem(tdq, td);
|
|
td->td_lastcpu = td->td_oncpu;
|
|
td->td_oncpu = NOCPU;
|
|
thread_lock_block(td);
|
|
|
|
newtd = sched_throw_grab(tdq);
|
|
|
|
/* doesn't return */
|
|
cpu_switch(td, newtd, TDQ_LOCKPTR(tdq));
|
|
}
|
|
|
|
/*
|
|
* This is called from fork_exit(). Just acquire the correct locks and
|
|
* let fork do the rest of the work.
|
|
*/
|
|
void
|
|
sched_fork_exit(struct thread *td)
|
|
{
|
|
struct tdq *tdq;
|
|
int cpuid;
|
|
|
|
/*
|
|
* Finish setting up thread glue so that it begins execution in a
|
|
* non-nested critical section with the scheduler lock held.
|
|
*/
|
|
KASSERT(curthread->td_md.md_spinlock_count == 1,
|
|
("invalid count %d", curthread->td_md.md_spinlock_count));
|
|
cpuid = PCPU_GET(cpuid);
|
|
tdq = TDQ_SELF();
|
|
TDQ_LOCK(tdq);
|
|
spinlock_exit();
|
|
MPASS(td->td_lock == TDQ_LOCKPTR(tdq));
|
|
td->td_oncpu = cpuid;
|
|
KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "running",
|
|
"prio:%d", td->td_priority);
|
|
SDT_PROBE0(sched, , , on__cpu);
|
|
}
|
|
|
|
/*
|
|
* Create on first use to catch odd startup conditions.
|
|
*/
|
|
char *
|
|
sched_tdname(struct thread *td)
|
|
{
|
|
#ifdef KTR
|
|
struct td_sched *ts;
|
|
|
|
ts = td_get_sched(td);
|
|
if (ts->ts_name[0] == '\0')
|
|
snprintf(ts->ts_name, sizeof(ts->ts_name),
|
|
"%s tid %d", td->td_name, td->td_tid);
|
|
return (ts->ts_name);
|
|
#else
|
|
return (td->td_name);
|
|
#endif
|
|
}
|
|
|
|
#ifdef KTR
|
|
void
|
|
sched_clear_tdname(struct thread *td)
|
|
{
|
|
struct td_sched *ts;
|
|
|
|
ts = td_get_sched(td);
|
|
ts->ts_name[0] = '\0';
|
|
}
|
|
#endif
|
|
|
|
#ifdef SMP
|
|
|
|
/*
|
|
* Build the CPU topology dump string. Is recursively called to collect
|
|
* the topology tree.
|
|
*/
|
|
static int
|
|
sysctl_kern_sched_topology_spec_internal(struct sbuf *sb, struct cpu_group *cg,
|
|
int indent)
|
|
{
|
|
char cpusetbuf[CPUSETBUFSIZ];
|
|
int i, first;
|
|
|
|
sbuf_printf(sb, "%*s<group level=\"%d\" cache-level=\"%d\">\n", indent,
|
|
"", 1 + indent / 2, cg->cg_level);
|
|
sbuf_printf(sb, "%*s <cpu count=\"%d\" mask=\"%s\">", indent, "",
|
|
cg->cg_count, cpusetobj_strprint(cpusetbuf, &cg->cg_mask));
|
|
first = TRUE;
|
|
for (i = cg->cg_first; i <= cg->cg_last; i++) {
|
|
if (CPU_ISSET(i, &cg->cg_mask)) {
|
|
if (!first)
|
|
sbuf_cat(sb, ", ");
|
|
else
|
|
first = FALSE;
|
|
sbuf_printf(sb, "%d", i);
|
|
}
|
|
}
|
|
sbuf_cat(sb, "</cpu>\n");
|
|
|
|
if (cg->cg_flags != 0) {
|
|
sbuf_printf(sb, "%*s <flags>", indent, "");
|
|
if ((cg->cg_flags & CG_FLAG_HTT) != 0)
|
|
sbuf_cat(sb, "<flag name=\"HTT\">HTT group</flag>");
|
|
if ((cg->cg_flags & CG_FLAG_THREAD) != 0)
|
|
sbuf_cat(sb, "<flag name=\"THREAD\">THREAD group</flag>");
|
|
if ((cg->cg_flags & CG_FLAG_SMT) != 0)
|
|
sbuf_cat(sb, "<flag name=\"SMT\">SMT group</flag>");
|
|
if ((cg->cg_flags & CG_FLAG_NODE) != 0)
|
|
sbuf_cat(sb, "<flag name=\"NODE\">NUMA node</flag>");
|
|
sbuf_cat(sb, "</flags>\n");
|
|
}
|
|
|
|
if (cg->cg_children > 0) {
|
|
sbuf_printf(sb, "%*s <children>\n", indent, "");
|
|
for (i = 0; i < cg->cg_children; i++)
|
|
sysctl_kern_sched_topology_spec_internal(sb,
|
|
&cg->cg_child[i], indent+2);
|
|
sbuf_printf(sb, "%*s </children>\n", indent, "");
|
|
}
|
|
sbuf_printf(sb, "%*s</group>\n", indent, "");
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Sysctl handler for retrieving topology dump. It's a wrapper for
|
|
* the recursive sysctl_kern_smp_topology_spec_internal().
|
|
*/
|
|
static int
|
|
sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
|
|
{
|
|
struct sbuf *topo;
|
|
int err;
|
|
|
|
KASSERT(cpu_top != NULL, ("cpu_top isn't initialized"));
|
|
|
|
topo = sbuf_new_for_sysctl(NULL, NULL, 512, req);
|
|
if (topo == NULL)
|
|
return (ENOMEM);
|
|
|
|
sbuf_cat(topo, "<groups>\n");
|
|
err = sysctl_kern_sched_topology_spec_internal(topo, cpu_top, 1);
|
|
sbuf_cat(topo, "</groups>\n");
|
|
|
|
if (err == 0) {
|
|
err = sbuf_finish(topo);
|
|
}
|
|
sbuf_delete(topo);
|
|
return (err);
|
|
}
|
|
|
|
#endif
|
|
|
|
static int
|
|
sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
|
|
{
|
|
int error, new_val, period;
|
|
|
|
period = 1000000 / realstathz;
|
|
new_val = period * sched_slice;
|
|
error = sysctl_handle_int(oidp, &new_val, 0, req);
|
|
if (error != 0 || req->newptr == NULL)
|
|
return (error);
|
|
if (new_val <= 0)
|
|
return (EINVAL);
|
|
sched_slice = imax(1, (new_val + period / 2) / period);
|
|
sched_slice_min = sched_slice / SCHED_SLICE_MIN_DIVISOR;
|
|
hogticks = imax(1, (2 * hz * sched_slice + realstathz / 2) /
|
|
realstathz);
|
|
return (0);
|
|
}
|
|
|
|
SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
|
|
"Scheduler");
|
|
SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "ULE", 0,
|
|
"Scheduler name");
|
|
SYSCTL_PROC(_kern_sched, OID_AUTO, quantum,
|
|
CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, 0,
|
|
sysctl_kern_quantum, "I",
|
|
"Quantum for timeshare threads in microseconds");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
|
|
"Quantum for timeshare threads in stathz ticks");
|
|
SYSCTL_UINT(_kern_sched, OID_AUTO, interact, CTLFLAG_RW, &sched_interact, 0,
|
|
"Interactivity score threshold");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, preempt_thresh, CTLFLAG_RW,
|
|
&preempt_thresh, 0,
|
|
"Maximal (lowest) priority for preemption");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, static_boost, CTLFLAG_RW, &static_boost, 0,
|
|
"Assign static kernel priorities to sleeping threads");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, idlespins, CTLFLAG_RW, &sched_idlespins, 0,
|
|
"Number of times idle thread will spin waiting for new work");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, idlespinthresh, CTLFLAG_RW,
|
|
&sched_idlespinthresh, 0,
|
|
"Threshold before we will permit idle thread spinning");
|
|
#ifdef SMP
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, affinity, CTLFLAG_RW, &affinity, 0,
|
|
"Number of hz ticks to keep thread affinity for");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, balance, CTLFLAG_RW, &rebalance, 0,
|
|
"Enables the long-term load balancer");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, balance_interval, CTLFLAG_RW,
|
|
&balance_interval, 0,
|
|
"Average period in stathz ticks to run the long-term balancer");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, steal_idle, CTLFLAG_RW, &steal_idle, 0,
|
|
"Attempts to steal work from other cores before idling");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
|
|
"Minimum load on remote CPU before we'll steal");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, trysteal_limit, CTLFLAG_RW, &trysteal_limit,
|
|
0, "Topological distance limit for stealing threads in sched_switch()");
|
|
SYSCTL_INT(_kern_sched, OID_AUTO, always_steal, CTLFLAG_RW, &always_steal, 0,
|
|
"Always run the stealer from the idle thread");
|
|
SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
|
|
CTLFLAG_MPSAFE | CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A",
|
|
"XML dump of detected CPU topology");
|
|
#endif
|
|
|
|
/* ps compat. All cpu percentages from ULE are weighted. */
|
|
static int ccpu = 0;
|
|
SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0,
|
|
"Decay factor used for updating %CPU in 4BSD scheduler");
|