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Date:      Sun, 25 Aug 2013 11:21:10 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-projects@freebsd.org
Subject:   svn commit: r254846 - projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs
Message-ID:  <201308251121.r7PBLA3v033536@svn.freebsd.org>
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Author: mav
Date: Sun Aug 25 11:21:10 2013
New Revision: 254846
URL: http://svnweb.freebsd.org/changeset/base/254846

Log:
  Allow GEOM direct dispatch for zvol providers.  Skip request handover to
  the worker thread if current context allows sleeping (thanks to the direct
  dispatch in action we are not in GEOM thread).
  
  Together this doubles zvol performance, reaching up to 300K IOPS on my tests.
  If there would be unmapped I/O support for zvols, the above value could be
  even bigger.

Modified:
  projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c

Modified: projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c
==============================================================================
--- projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c	Sun Aug 25 11:21:03 2013	(r254845)
+++ projects/camlock/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zvol.c	Sun Aug 25 11:21:10 2013	(r254846)
@@ -2068,6 +2068,7 @@ zvol_geom_create(const char *name)
 	gp->start = zvol_geom_start;
 	gp->access = zvol_geom_access;
 	pp = g_new_providerf(gp, "%s/%s", ZVOL_DRIVER, name);
+	pp->flags |= G_PF_DIRECT_RECEIVE | G_PF_DIRECT_SEND;
 	pp->sectorsize = DEV_BSIZE;
 
 	zv = kmem_zalloc(sizeof(*zv), KM_SLEEP);
@@ -2171,18 +2172,20 @@ zvol_geom_start(struct bio *bp)
 	zvol_state_t *zv;
 	boolean_t first;
 
+	zv = bp->bio_to->private;
+	ASSERT(zv != NULL);
 	switch (bp->bio_cmd) {
+	case BIO_FLUSH:
+		if (curthread->td_no_sleeping != 0)
+			goto enqueue;
+		zil_commit(zv->zv_zilog, ZVOL_OBJ);
+		g_io_deliver(bp, 0);
+		break;
 	case BIO_READ:
 	case BIO_WRITE:
-	case BIO_FLUSH:
-		zv = bp->bio_to->private;
-		ASSERT(zv != NULL);
-		mtx_lock(&zv->zv_queue_mtx);
-		first = (bioq_first(&zv->zv_queue) == NULL);
-		bioq_insert_tail(&zv->zv_queue, bp);
-		mtx_unlock(&zv->zv_queue_mtx);
-		if (first)
-			wakeup_one(&zv->zv_queue);
+		if (curthread->td_no_sleeping != 0)
+			goto enqueue;
+		zvol_strategy(bp);
 		break;
 	case BIO_GETATTR:
 	case BIO_DELETE:
@@ -2190,6 +2193,15 @@ zvol_geom_start(struct bio *bp)
 		g_io_deliver(bp, EOPNOTSUPP);
 		break;
 	}
+	return;
+
+enqueue:
+	mtx_lock(&zv->zv_queue_mtx);
+	first = (bioq_first(&zv->zv_queue) == NULL);
+	bioq_insert_tail(&zv->zv_queue, bp);
+	mtx_unlock(&zv->zv_queue_mtx);
+	if (first)
+		wakeup_one(&zv->zv_queue);
 }
 
 static void
@@ -2364,6 +2376,7 @@ zvol_rename_minor(struct g_geom *gp, con
 	g_wither_provider(pp, ENXIO);
 
 	pp = g_new_providerf(gp, "%s/%s", ZVOL_DRIVER, newname);
+	pp->flags |= G_PF_DIRECT_RECEIVE | G_PF_DIRECT_SEND;
 	pp->sectorsize = DEV_BSIZE;
 	pp->mediasize = zv->zv_volsize;
 	pp->private = zv;

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