Update all default taskq settings

Over the years the default values for the taskqs used on Linux have
differed slightly from illumos.  In the vast majority of cases this
was done to avoid creating an obnoxious number of idle threads which
would pollute the process listing.

With the addition of support for dynamic taskqs all multi-threaded
queues should be created as dynamic taskqs.  This allows us to get
the best of both worlds.

* The illumos default values for the I/O pipeline can be restored.
These values are known to work well for most workloads.  The only
exception is the zio write interrupt taskq which is changed to
ZTI_P(12, 8).  At least under Linux more threads has been shown
to improve performance, see commit 7e55f4e.

* Reduces the number of idle threads on the system when it's not
under heavy load.  The maximum number of threads will only be
created when they are required.

* Remove the vdev_file_taskq and rely on the system_taskq instead
which is now dynamic and may have up to 64-threads.  Again this
brings us back inline with upstream.

* Tasks dispatched with taskq_dispatch_ent() are allowed to use
dynamic taskqs.  The Linux taskq implementation supports this.

Signed-off-by: Brian Behlendorf <[email protected]>
Signed-off-by: Tim Chase <[email protected]>
Closes #3507

8 files changed, 12 insertions, 31 deletions

diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 16d970672..99fa69872 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -5002,7 +5002,7 @@ arc_init(void)
 	bzero(&arc_eviction_hdr, sizeof (arc_buf_hdr_t));
 
 	arc_prune_taskq = taskq_create("arc_prune", max_ncpus, minclsyspri,
-	    max_ncpus, INT_MAX, TASKQ_PREPOPULATE);
+	    max_ncpus, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 
 	arc_ksp = kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED,
 	    sizeof (arc_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
diff --git a/module/zfs/dsl_pool.c b/module/zfs/dsl_pool.c
index 908c44e70..5d804352d 100644
--- a/module/zfs/dsl_pool.c
+++ b/module/zfs/dsl_pool.c
@@ -171,7 +171,7 @@ dsl_pool_open_impl(spa_t *spa, uint64_t txg)
 	cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
 
 	dp->dp_iput_taskq = taskq_create("z_iput", max_ncpus, minclsyspri,
-	    max_ncpus * 8, INT_MAX, TASKQ_PREPOPULATE);
+	    max_ncpus * 8, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 
 	return (dp);
 }
diff --git a/module/zfs/metaslab.c b/module/zfs/metaslab.c
index 3b556b6db..d6ee81c85 100644
--- a/module/zfs/metaslab.c
+++ b/module/zfs/metaslab.c
@@ -492,7 +492,7 @@ metaslab_group_create(metaslab_class_t *mc, vdev_t *vd)
 	mg->mg_activation_count = 0;
 
 	mg->mg_taskq = taskq_create("metaslab_group_taskq", metaslab_load_pct,
-	    minclsyspri, 10, INT_MAX, TASKQ_THREADS_CPU_PCT);
+	    minclsyspri, 10, INT_MAX, TASKQ_THREADS_CPU_PCT | TASKQ_DYNAMIC);
 
 	return (mg);
 }
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index ad109a641..b5e024c3f 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -127,9 +127,9 @@ static const char *const zio_taskq_types[ZIO_TASKQ_TYPES] = {
 const zio_taskq_info_t zio_taskqs[ZIO_TYPES][ZIO_TASKQ_TYPES] = {
 	/* ISSUE	ISSUE_HIGH	INTR		INTR_HIGH */
 	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* NULL */
-	{ ZTI_N(8),	ZTI_NULL,	ZTI_BATCH,	ZTI_NULL }, /* READ */
-	{ ZTI_BATCH,	ZTI_N(5),	ZTI_N(16),	ZTI_N(5) }, /* WRITE */
-	{ ZTI_P(4, 8),	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* FREE */
+	{ ZTI_N(8),	ZTI_NULL,	ZTI_P(12, 8),	ZTI_NULL }, /* READ */
+	{ ZTI_BATCH,	ZTI_N(5),	ZTI_P(12, 8),	ZTI_N(5) }, /* WRITE */
+	{ ZTI_P(12, 8),	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* FREE */
 	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* CLAIM */
 	{ ZTI_ONE,	ZTI_NULL,	ZTI_ONE,	ZTI_NULL }, /* IOCTL */
 };
@@ -844,7 +844,7 @@ spa_taskqs_init(spa_t *spa, zio_type_t t, zio_taskq_type_t q)
 	uint_t count = ztip->zti_count;
 	spa_taskqs_t *tqs = &spa->spa_zio_taskq[t][q];
 	char name[32];
-	uint_t i, flags = 0;
+	uint_t i, flags = TASKQ_DYNAMIC;
 	boolean_t batch = B_FALSE;
 
 	if (mode == ZTI_MODE_NULL) {
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index 26b6f1731..ad9f9fe28 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -1829,7 +1829,6 @@ spa_init(int mode)
 	dmu_init();
 	zil_init();
 	vdev_cache_stat_init();
-	vdev_file_init();
 	zfs_prop_init();
 	zpool_prop_init();
 	zpool_feature_init();
@@ -1844,7 +1843,6 @@ spa_fini(void)
 
 	spa_evict_all();
 
-	vdev_file_fini();
 	vdev_cache_stat_fini();
 	zil_fini();
 	dmu_fini();
diff --git a/module/zfs/txg.c b/module/zfs/txg.c
index 9accd48df..7681856ea 100644
--- a/module/zfs/txg.c
+++ b/module/zfs/txg.c
@@ -445,8 +445,8 @@ txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
 			 * Commit callback taskq hasn't been created yet.
 			 */
 			tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
-			    100, minclsyspri, max_ncpus, INT_MAX,
-			    TASKQ_THREADS_CPU_PCT | TASKQ_PREPOPULATE);
+			    max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2,
+			    TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 		}
 
 		cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
diff --git a/module/zfs/vdev_file.c b/module/zfs/vdev_file.c
index 3c3a13993..e61240fdc 100644
--- a/module/zfs/vdev_file.c
+++ b/module/zfs/vdev_file.c
@@ -36,8 +36,6 @@
  * Virtual device vector for files.
  */
 
-static taskq_t *vdev_file_taskq;
-
 static void
 vdev_file_hold(vdev_t *vd)
 {
@@ -200,7 +198,7 @@ vdev_file_io_start(zio_t *zio)
 			 * the sync must be dispatched to a different context.
 			 */
 			if (spl_fstrans_check()) {
-				VERIFY3U(taskq_dispatch(vdev_file_taskq,
+				VERIFY3U(taskq_dispatch(system_taskq,
 				    vdev_file_io_fsync, zio, TQ_SLEEP), !=, 0);
 				return;
 			}
@@ -216,7 +214,7 @@ vdev_file_io_start(zio_t *zio)
 		return;
 	}
 
-	VERIFY3U(taskq_dispatch(vdev_file_taskq, vdev_file_io_strategy, zio,
+	VERIFY3U(taskq_dispatch(system_taskq, vdev_file_io_strategy, zio,
 	    TQ_SLEEP), !=, 0);
 }
 
@@ -239,21 +237,6 @@ vdev_ops_t vdev_file_ops = {
 	B_TRUE			/* leaf vdev */
 };
 
-void
-vdev_file_init(void)
-{
-	vdev_file_taskq = taskq_create("vdev_file_taskq", 100, minclsyspri,
-	    max_ncpus, INT_MAX, TASKQ_PREPOPULATE | TASKQ_THREADS_CPU_PCT);
-
-	VERIFY(vdev_file_taskq);
-}
-
-void
-vdev_file_fini(void)
-{
-	taskq_destroy(vdev_file_taskq);
-}
-
 /*
  * From userland we access disks just like files.
  */
diff --git a/module/zfs/zvol.c b/module/zfs/zvol.c
index d180b5b5b..8646892ea 100644
--- a/module/zfs/zvol.c
+++ b/module/zfs/zvol.c
@@ -1632,7 +1632,7 @@ zvol_init(void)
 	mutex_init(&zvol_state_lock, NULL, MUTEX_DEFAULT, NULL);
 
 	zvol_taskq = taskq_create(ZVOL_DRIVER, zvol_threads, maxclsyspri,
-	    zvol_threads, INT_MAX, TASKQ_PREPOPULATE);
+	    zvol_threads * 2, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
 	if (zvol_taskq == NULL) {
 		printk(KERN_INFO "ZFS: taskq_create() failed\n");
 		error = -ENOMEM;