From 711f661393c0f971d750a262d0548c9550f4a5bc Mon Sep 17 00:00:00 2001
From: Alexander Motin <mav@FreeBSD.org>
Date: Sat, 12 May 2012 13:55:36 +0000
Subject: [PATCH] Add two functions xpt_batch_start() and xpt_batch_done() to
 the CAM SIM KPI to allow drivers to handle request completion directly
 without passing them to the CAM SWI thread removing extra context switch.
 Modify all ATA/SATA drivers to use them.

Reviewed by:	gibbs, ken
MFC after:	2 weeks
---
 sys/cam/cam_sim.h     |  1 +
 sys/cam/cam_xpt.c     | 22 +++++++++++++++++++++-
 sys/cam/cam_xpt_sim.h |  2 ++
 sys/dev/ahci/ahci.c   |  2 ++
 sys/dev/ata/ata-all.c |  2 ++
 sys/dev/mvs/mvs.c     |  2 ++
 sys/dev/siis/siis.c   |  2 ++
 7 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/sys/cam/cam_sim.h b/sys/cam/cam_sim.h
index 398d5403403d..93e99a5cedaf 100644
--- a/sys/cam/cam_sim.h
+++ b/sys/cam/cam_sim.h
@@ -106,6 +106,7 @@ struct cam_sim {
 #define	CAM_SIM_MPSAFE			0x02
 #define	CAM_SIM_ON_DONEQ		0x04
 #define	CAM_SIM_POLLED			0x08
+#define	CAM_SIM_BATCH			0x10
 	struct callout		callout;
 	struct cam_devq 	*devq;	/* Device Queue to use for this SIM */
 	int			refcount; /* References to the SIM. */
diff --git a/sys/cam/cam_xpt.c b/sys/cam/cam_xpt.c
index 0ee1cc4f0e7f..b984e9a72002 100644
--- a/sys/cam/cam_xpt.c
+++ b/sys/cam/cam_xpt.c
@@ -4332,7 +4332,8 @@ xpt_done(union ccb *done_ccb)
 		TAILQ_INSERT_TAIL(&sim->sim_doneq, &done_ccb->ccb_h,
 		    sim_links.tqe);
 		done_ccb->ccb_h.pinfo.index = CAM_DONEQ_INDEX;
-		if ((sim->flags & (CAM_SIM_ON_DONEQ | CAM_SIM_POLLED)) == 0) {
+		if ((sim->flags & (CAM_SIM_ON_DONEQ | CAM_SIM_POLLED |
+		    CAM_SIM_BATCH)) == 0) {
 			mtx_lock(&cam_simq_lock);
 			first = TAILQ_EMPTY(&cam_simq);
 			TAILQ_INSERT_TAIL(&cam_simq, sim, links);
@@ -4344,6 +4345,25 @@ xpt_done(union ccb *done_ccb)
 	}
 }
 
+void
+xpt_batch_start(struct cam_sim *sim)
+{
+
+	KASSERT((sim->flags & CAM_SIM_BATCH) == 0, ("Batch flag already set"));
+	sim->flags |= CAM_SIM_BATCH;
+}
+
+void
+xpt_batch_done(struct cam_sim *sim)
+{
+
+	KASSERT((sim->flags & CAM_SIM_BATCH) != 0, ("Batch flag was not set"));
+	sim->flags &= ~CAM_SIM_BATCH;
+	if (!TAILQ_EMPTY(&sim->sim_doneq) &&
+	    (sim->flags & CAM_SIM_ON_DONEQ) == 0)
+		camisr_runqueue(&sim->sim_doneq);
+}
+
 union ccb *
 xpt_alloc_ccb()
 {
diff --git a/sys/cam/cam_xpt_sim.h b/sys/cam/cam_xpt_sim.h
index 323f786c813f..67b895f2e75e 100644
--- a/sys/cam/cam_xpt_sim.h
+++ b/sys/cam/cam_xpt_sim.h
@@ -51,6 +51,8 @@ void		xpt_release_devq_rl(struct cam_path *path, cam_rl rl,
 		    u_int count, int run_queue);
 int		xpt_sim_opened(struct cam_sim *sim);
 void		xpt_done(union ccb *done_ccb);
+void		xpt_batch_start(struct cam_sim *sim);
+void		xpt_batch_done(struct cam_sim *sim);
 #endif
 
 #endif /* _CAM_CAM_XPT_SIM_H */
diff --git a/sys/dev/ahci/ahci.c b/sys/dev/ahci/ahci.c
index c3557366c320..796dc3364f97 100644
--- a/sys/dev/ahci/ahci.c
+++ b/sys/dev/ahci/ahci.c
@@ -1457,7 +1457,9 @@ ahci_ch_intr_locked(void *data)
 	struct ahci_channel *ch = device_get_softc(dev);
 
 	mtx_lock(&ch->mtx);
+	xpt_batch_start(ch->sim);
 	ahci_ch_intr(data);
+	xpt_batch_done(ch->sim);
 	mtx_unlock(&ch->mtx);
 }
 
diff --git a/sys/dev/ata/ata-all.c b/sys/dev/ata/ata-all.c
index 9ea25c0495e2..3caad019faed 100644
--- a/sys/dev/ata/ata-all.c
+++ b/sys/dev/ata/ata-all.c
@@ -544,9 +544,11 @@ ata_interrupt(void *data)
     struct ata_channel *ch = (struct ata_channel *)data;
 
     mtx_lock(&ch->state_mtx);
+    xpt_batch_start(ch->sim);
 #endif
     ata_interrupt_locked(data);
 #ifdef ATA_CAM
+    xpt_batch_done(ch->sim);
     mtx_unlock(&ch->state_mtx);
 #endif
 }
diff --git a/sys/dev/mvs/mvs.c b/sys/dev/mvs/mvs.c
index e128616e7038..debe55af4b76 100644
--- a/sys/dev/mvs/mvs.c
+++ b/sys/dev/mvs/mvs.c
@@ -654,7 +654,9 @@ mvs_ch_intr_locked(void *data)
 	struct mvs_channel *ch = device_get_softc(dev);
 
 	mtx_lock(&ch->mtx);
+	xpt_batch_start(ch->sim);
 	mvs_ch_intr(data);
+	xpt_batch_done(ch->sim);
 	mtx_unlock(&ch->mtx);
 }
 
diff --git a/sys/dev/siis/siis.c b/sys/dev/siis/siis.c
index 17c1a39ef933..2b709cd9693d 100644
--- a/sys/dev/siis/siis.c
+++ b/sys/dev/siis/siis.c
@@ -830,7 +830,9 @@ siis_ch_intr_locked(void *data)
 	struct siis_channel *ch = device_get_softc(dev);
 
 	mtx_lock(&ch->mtx);
+	xpt_batch_start(ch->sim);
 	siis_ch_intr(data);
+	xpt_batch_done(ch->sim);
 	mtx_unlock(&ch->mtx);
 }