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vm: Remove kernel stack swapping support, part 1

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- Disconnect the swapout daemon from the page daemon.
- Remove swapout() and swapout_procs().

Tested by:	pho
Reviewed by:	alc, imp, kib
Differential Revision:	https://reviews.freebsd.org/D46112
This commit is contained in:
Mark Johnston 2024-07-29 01:38:21 +00:00
parent 7186765300
commit 13a1129d70
4 changed files with 1 additions and 263 deletions
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12
sys/vm/vm_pageout.c
View File

@ -1764,24 +1764,12 @@ vm_pageout_inactive(struct vm_domain *vmd, int shortage, int *addl_shortage)
vm_pagequeue_unlock(pq);
}
/*
* Wakeup the swapout daemon if we didn't free the targeted number of
* pages.
*/
if (page_shortage > 0)
vm_swapout_run();
/*
* If the inactive queue scan fails repeatedly to meet its
* target, kill the largest process.
*/
vm_pageout_mightbe_oom(vmd, page_shortage, starting_page_shortage);
/*
* Reclaim pages by swapping out idle processes, if configured to do so.
*/
vm_swapout_run_idle();
/*
* See the description of addl_page_shortage above.
*/

3
sys/vm/vm_pageout.h
View File

@ -103,8 +103,5 @@ void vm_wait_severe(void);
int vm_pageout_flush(vm_page_t *, int, int, int, int *, boolean_t *);
void vm_pageout_oom(int shortage);
void vm_swapout_run(void);
void vm_swapout_run_idle(void);
#endif /* _KERNEL */
#endif /* _VM_VM_PAGEOUT_H_ */

239
sys/vm/vm_swapout.c
View File

@ -154,7 +154,6 @@ SYSCTL_INT(_vm, OID_AUTO, vmdaemon_timeout, CTLFLAG_RW,
&vm_daemon_timeout, 0,
"Time between vmdaemon runs");
static int vm_pageout_req_swapout; /* XXX */
static int vm_daemon_needed;
static struct mtx vm_daemon_mtx;
/* Allow for use by vm_pageout before vm_daemon is initialized. */
@ -165,12 +164,8 @@ static int swap_inprogress; /* Pending swap-ins done outside swapper. */
static int last_swapin;
static void swapclear(struct proc *);
static int swapout(struct proc *);
static void vm_swapout_map_deactivate_pages(vm_map_t, long);
static void vm_swapout_object_deactivate(pmap_t, vm_object_t, long);
static void swapout_procs(int action);
static void vm_req_vmdaemon(int req);
static void vm_thread_swapout(struct thread *td);
static void
vm_swapout_object_deactivate_page(pmap_t pmap, vm_page_t m, bool unmap)
@ -322,49 +317,6 @@ vm_swapout_map_deactivate_pages(vm_map_t map, long desired)
vm_map_unlock_read(map);
}
/*
* Swap out requests
*/
#define VM_SWAP_NORMAL 1
#define VM_SWAP_IDLE 2
void
vm_swapout_run(void)
{
if (vm_swap_enabled)
vm_req_vmdaemon(VM_SWAP_NORMAL);
}
/*
* Idle process swapout -- run once per second when pagedaemons are
* reclaiming pages.
*/
void
vm_swapout_run_idle(void)
{
static long lsec;
if (!vm_swap_idle_enabled || time_second == lsec)
return;
vm_req_vmdaemon(VM_SWAP_IDLE);
lsec = time_second;
}
static void
vm_req_vmdaemon(int req)
{
static int lastrun = 0;
mtx_lock(&vm_daemon_mtx);
vm_pageout_req_swapout |= req;
if ((ticks > (lastrun + hz)) || (ticks < lastrun)) {
wakeup(&vm_daemon_needed);
lastrun = ticks;
}
mtx_unlock(&vm_daemon_mtx);
}
static void
vm_daemon(void)
{
@ -372,7 +324,7 @@ vm_daemon(void)
struct proc *p;
struct thread *td;
struct vmspace *vm;
int breakout, swapout_flags, tryagain, attempts;
int breakout, tryagain, attempts;
#ifdef RACCT
uint64_t rsize, ravailable;
@ -384,18 +336,7 @@ vm_daemon(void)
mtx_lock(&vm_daemon_mtx);
msleep(&vm_daemon_needed, &vm_daemon_mtx, PPAUSE, "psleep",
vm_daemon_timeout);
swapout_flags = vm_pageout_req_swapout;
vm_pageout_req_swapout = 0;
mtx_unlock(&vm_daemon_mtx);
if (swapout_flags != 0) {
/*
* Drain the per-CPU page queue batches as a deadlock
* avoidance measure.
*/
if ((swapout_flags & VM_SWAP_NORMAL) != 0)
vm_page_pqbatch_drain();
swapout_procs(swapout_flags);
}
/*
* scan the processes for exceeding their rlimits or if
@ -520,36 +461,6 @@ again:
}
}
/*
* Allow a thread's kernel stack to be paged out.
*/
static void
vm_thread_swapout(struct thread *td)
{
vm_page_t m;
vm_offset_t kaddr;
vm_pindex_t pindex;
int i, pages;
vm_object_t obj;
cpu_thread_swapout(td);
kaddr = td->td_kstack;
pages = td->td_kstack_pages;
obj = vm_thread_kstack_size_to_obj(pages);
pindex = vm_kstack_pindex(kaddr, pages);
pmap_qremove(kaddr, pages);
VM_OBJECT_WLOCK(obj);
for (i = 0; i < pages; i++) {
m = vm_page_lookup(obj, pindex + i);
if (m == NULL)
panic("vm_thread_swapout: kstack already missing?");
vm_page_dirty(m);
vm_page_xunbusy_unchecked(m);
vm_page_unwire(m, PQ_LAUNDRY);
}
VM_OBJECT_WUNLOCK(obj);
}
/*
* Bring the kernel stack for a specified thread back in.
*/
@ -773,100 +684,6 @@ swapper(void)
}
}
/*
* First, if any processes have been sleeping or stopped for at least
* "swap_idle_threshold1" seconds, they are swapped out. If, however,
* no such processes exist, then the longest-sleeping or stopped
* process is swapped out. Finally, and only as a last resort, if
* there are no sleeping or stopped processes, the longest-resident
* process is swapped out.
*/
static void
swapout_procs(int action)
{
struct proc *p;
struct thread *td;
int slptime;
bool didswap, doswap;
MPASS((action & (VM_SWAP_NORMAL | VM_SWAP_IDLE)) != 0);
didswap = false;
sx_slock(&allproc_lock);
FOREACH_PROC_IN_SYSTEM(p) {
/*
* Filter out not yet fully constructed processes. Do
* not swap out held processes. Avoid processes which
* are system, exiting, execing, traced, already swapped
* out or are in the process of being swapped in or out.
*/
PROC_LOCK(p);
if (p->p_state != PRS_NORMAL || p->p_lock != 0 || (p->p_flag &
(P_SYSTEM | P_WEXIT | P_INEXEC | P_STOPPED_SINGLE |
P_TRACED | P_SWAPPINGOUT | P_SWAPPINGIN | P_INMEM)) !=
P_INMEM) {
PROC_UNLOCK(p);
continue;
}
/*
* Further consideration of this process for swap out
* requires iterating over its threads. We release
* allproc_lock here so that process creation and
* destruction are not blocked while we iterate.
*
* To later reacquire allproc_lock and resume
* iteration over the allproc list, we will first have
* to release the lock on the process. We place a
* hold on the process so that it remains in the
* allproc list while it is unlocked.
*/
_PHOLD_LITE(p);
sx_sunlock(&allproc_lock);
/*
* Do not swapout a realtime process.
* Guarantee swap_idle_threshold1 time in memory.
* If the system is under memory stress, or if we are
* swapping idle processes >= swap_idle_threshold2,
* then swap the process out.
*/
doswap = true;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
slptime = (ticks - td->td_slptick) / hz;
if (PRI_IS_REALTIME(td->td_pri_class) ||
slptime < swap_idle_threshold1 ||
!thread_safetoswapout(td) ||
((action & VM_SWAP_NORMAL) == 0 &&
slptime < swap_idle_threshold2))
doswap = false;
thread_unlock(td);
if (!doswap)
break;
}
if (doswap && swapout(p) == 0)
didswap = true;
PROC_UNLOCK(p);
if (didswap) {
sx_xlock(&allproc_lock);
swapped_cnt++;
sx_downgrade(&allproc_lock);
} else
sx_slock(&allproc_lock);
PRELE(p);
}
sx_sunlock(&allproc_lock);
/*
* If we swapped something out, and another process needed memory,
* then wakeup the sched process.
*/
if (didswap)
wakeup(&proc0);
}
static void
swapclear(struct proc *p)
{
@ -896,57 +713,3 @@ swapclear(struct proc *p)
p->p_flag &= ~(P_SWAPPINGIN | P_SWAPPINGOUT);
p->p_flag |= P_INMEM;
}
static int
swapout(struct proc *p)
{
struct thread *td;
PROC_LOCK_ASSERT(p, MA_OWNED);
/*
* The states of this process and its threads may have changed
* by now. Assuming that there is only one pageout daemon thread,
* this process should still be in memory.
*/
KASSERT((p->p_flag & (P_INMEM | P_SWAPPINGOUT | P_SWAPPINGIN)) ==
P_INMEM, ("swapout: lost a swapout race?"));
/*
* Remember the resident count.
*/
p->p_vmspace->vm_swrss = vmspace_resident_count(p->p_vmspace);
/*
* Check and mark all threads before we proceed.
*/
p->p_flag &= ~P_INMEM;
p->p_flag |= P_SWAPPINGOUT;
FOREACH_THREAD_IN_PROC(p, td) {
thread_lock(td);
if (!thread_safetoswapout(td)) {
thread_unlock(td);
swapclear(p);
return (EBUSY);
}
td->td_flags &= ~TDF_INMEM;
TD_SET_SWAPPED(td);
thread_unlock(td);
}
td = FIRST_THREAD_IN_PROC(p);
++td->td_ru.ru_nswap;
PROC_UNLOCK(p);
/*
* This list is stable because all threads are now prevented from
* running. The list is only modified in the context of a running
* thread in this process.
*/
FOREACH_THREAD_IN_PROC(p, td)
vm_thread_swapout(td);
PROC_LOCK(p);
p->p_flag &= ~P_SWAPPINGOUT;
p->p_swtick = ticks;
return (0);
}

10
sys/vm/vm_swapout_dummy.c
View File

@ -91,16 +91,6 @@ SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, CTLFLAG_RD,
&vm_swap_idle_enabled, 0,
"Allow swapout on idle criteria");
void
vm_swapout_run(void)
{
}
void
vm_swapout_run_idle(void)
{
}
void
faultin(struct proc *p)
{