Remove pool io kstats (#12212)

This mostly reverts "3537 want pool io kstats" commit of 8 years ago.

From one side this code using pool-wide locks became pretty bad for
performance, creating significant lock contention in I/O pipeline.
From another, there are more efficient ways now to obtain detailed
statistics, while this statistics is illumos-specific and much less
usable on Linux and FreeBSD, reported only via procfs/sysctls.

This commit does not remove KSTAT_TYPE_IO implementation, that may
be removed later together with already unused KSTAT_TYPE_INTR and
KSTAT_TYPE_TIMER.

Reviewed-by: Matthew Ahrens <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Alexander Motin <[email protected]>
Sponsored-By: iXsystems, Inc.
Closes #12212 

4 files changed, 0 insertions, 225 deletions

diff --git a/module/os/freebsd/spl/spl_kstat.c b/module/os/freebsd/spl/spl_kstat.c
index e591921ac..059ada235 100644
--- a/module/os/freebsd/spl/spl_kstat.c
+++ b/module/os/freebsd/spl/spl_kstat.c
@@ -508,65 +508,3 @@ kstat_delete(kstat_t *ksp)
 		kmem_free(ksp->ks_data, ksp->ks_data_size);
 	free(ksp, M_KSTAT);
 }
-
-void
-kstat_waitq_enter(kstat_io_t *kiop)
-{
-	hrtime_t new, delta;
-	ulong_t wcnt;
-
-	new = gethrtime();
-	delta = new - kiop->wlastupdate;
-	kiop->wlastupdate = new;
-	wcnt = kiop->wcnt++;
-	if (wcnt != 0) {
-		kiop->wlentime += delta * wcnt;
-		kiop->wtime += delta;
-	}
-}
-
-void
-kstat_waitq_exit(kstat_io_t *kiop)
-{
-	hrtime_t new, delta;
-	ulong_t wcnt;
-
-	new = gethrtime();
-	delta = new - kiop->wlastupdate;
-	kiop->wlastupdate = new;
-	wcnt = kiop->wcnt--;
-	ASSERT3S(wcnt, >, 0);
-	kiop->wlentime += delta * wcnt;
-	kiop->wtime += delta;
-}
-
-void
-kstat_runq_enter(kstat_io_t *kiop)
-{
-	hrtime_t new, delta;
-	ulong_t rcnt;
-
-	new = gethrtime();
-	delta = new - kiop->rlastupdate;
-	kiop->rlastupdate = new;
-	rcnt = kiop->rcnt++;
-	if (rcnt != 0) {
-		kiop->rlentime += delta * rcnt;
-		kiop->rtime += delta;
-	}
-}
-
-void
-kstat_runq_exit(kstat_io_t *kiop)
-{
-	hrtime_t new, delta;
-	ulong_t rcnt;
-
-	new = gethrtime();
-	delta = new - kiop->rlastupdate;
-	kiop->rlastupdate = new;
-	rcnt = kiop->rcnt--;
-	ASSERT3S(rcnt, >, 0);
-	kiop->rlentime += delta * rcnt;
-	kiop->rtime += delta;
-}
diff --git a/module/os/linux/spl/spl-kstat.c b/module/os/linux/spl/spl-kstat.c
index c7f1aadf7..0c4670832 100644
--- a/module/os/linux/spl/spl-kstat.c
+++ b/module/os/linux/spl/spl-kstat.c
@@ -50,72 +50,6 @@ kstat_resize_raw(kstat_t *ksp)
 	return (0);
 }
 
-void
-kstat_waitq_enter(kstat_io_t *kiop)
-{
-	hrtime_t new, delta;
-	ulong_t wcnt;
-
-	new = gethrtime();
-	delta = new - kiop->wlastupdate;
-	kiop->wlastupdate = new;
-	wcnt = kiop->wcnt++;
-	if (wcnt != 0) {
-		kiop->wlentime += delta * wcnt;
-		kiop->wtime += delta;
-	}
-}
-EXPORT_SYMBOL(kstat_waitq_enter);
-
-void
-kstat_waitq_exit(kstat_io_t *kiop)
-{
-	hrtime_t new, delta;
-	ulong_t wcnt;
-
-	new = gethrtime();
-	delta = new - kiop->wlastupdate;
-	kiop->wlastupdate = new;
-	wcnt = kiop->wcnt--;
-	ASSERT((int)wcnt > 0);
-	kiop->wlentime += delta * wcnt;
-	kiop->wtime += delta;
-}
-EXPORT_SYMBOL(kstat_waitq_exit);
-
-void
-kstat_runq_enter(kstat_io_t *kiop)
-{
-	hrtime_t new, delta;
-	ulong_t rcnt;
-
-	new = gethrtime();
-	delta = new - kiop->rlastupdate;
-	kiop->rlastupdate = new;
-	rcnt = kiop->rcnt++;
-	if (rcnt != 0) {
-		kiop->rlentime += delta * rcnt;
-		kiop->rtime += delta;
-	}
-}
-EXPORT_SYMBOL(kstat_runq_enter);
-
-void
-kstat_runq_exit(kstat_io_t *kiop)
-{
-	hrtime_t new, delta;
-	ulong_t rcnt;
-
-	new = gethrtime();
-	delta = new - kiop->rlastupdate;
-	kiop->rlastupdate = new;
-	rcnt = kiop->rcnt--;
-	ASSERT((int)rcnt > 0);
-	kiop->rlentime += delta * rcnt;
-	kiop->rtime += delta;
-}
-EXPORT_SYMBOL(kstat_runq_exit);
-
 static int
 kstat_seq_show_headers(struct seq_file *f)
 {
diff --git a/module/zfs/spa_stats.c b/module/zfs/spa_stats.c
index c3eacc142..534ac72fe 100644
--- a/module/zfs/spa_stats.c
+++ b/module/zfs/spa_stats.c
@@ -550,54 +550,6 @@ spa_tx_assign_add_nsecs(spa_t *spa, uint64_t nsecs)
 
 /*
  * ==========================================================================
- * SPA IO History Routines
- * ==========================================================================
- */
-static int
-spa_io_history_update(kstat_t *ksp, int rw)
-{
-	if (rw == KSTAT_WRITE)
-		memset(ksp->ks_data, 0, ksp->ks_data_size);
-
-	return (0);
-}
-
-static void
-spa_io_history_init(spa_t *spa)
-{
-	spa_history_kstat_t *shk = &spa->spa_stats.io_history;
-	char *name;
-	kstat_t *ksp;
-
-	mutex_init(&shk->lock, NULL, MUTEX_DEFAULT, NULL);
-
-	name = kmem_asprintf("zfs/%s", spa_name(spa));
-
-	ksp = kstat_create(name, 0, "io", "disk", KSTAT_TYPE_IO, 1, 0);
-	shk->kstat = ksp;
-
-	if (ksp) {
-		ksp->ks_lock = &shk->lock;
-		ksp->ks_private = spa;
-		ksp->ks_update = spa_io_history_update;
-		kstat_install(ksp);
-	}
-	kmem_strfree(name);
-}
-
-static void
-spa_io_history_destroy(spa_t *spa)
-{
-	spa_history_kstat_t *shk = &spa->spa_stats.io_history;
-
-	if (shk->kstat)
-		kstat_delete(shk->kstat);
-
-	mutex_destroy(&shk->lock);
-}
-
-/*
- * ==========================================================================
  * SPA MMP History Routines
  * ==========================================================================
  */
@@ -996,7 +948,6 @@ spa_stats_init(spa_t *spa)
 	spa_read_history_init(spa);
 	spa_txg_history_init(spa);
 	spa_tx_assign_init(spa);
-	spa_io_history_init(spa);
 	spa_mmp_history_init(spa);
 	spa_state_init(spa);
 	spa_iostats_init(spa);
@@ -1010,7 +961,6 @@ spa_stats_destroy(spa_t *spa)
 	spa_tx_assign_destroy(spa);
 	spa_txg_history_destroy(spa);
 	spa_read_history_destroy(spa);
-	spa_io_history_destroy(spa);
 	spa_mmp_history_destroy(spa);
 }
 
diff --git a/module/zfs/vdev_queue.c b/module/zfs/vdev_queue.c
index 25a4bc69c..198861edb 100644
--- a/module/zfs/vdev_queue.c
+++ b/module/zfs/vdev_queue.c
@@ -35,8 +35,6 @@
 #include <sys/dsl_pool.h>
 #include <sys/metaslab_impl.h>
 #include <sys/spa.h>
-#include <sys/spa_impl.h>
-#include <sys/kstat.h>
 #include <sys/abd.h>
 
 /*
@@ -516,35 +514,17 @@ vdev_queue_fini(vdev_t *vd)
 static void
 vdev_queue_io_add(vdev_queue_t *vq, zio_t *zio)
 {
-	spa_t *spa = zio->io_spa;
-	spa_history_kstat_t *shk = &spa->spa_stats.io_history;
-
 	ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE);
 	avl_add(vdev_queue_class_tree(vq, zio->io_priority), zio);
 	avl_add(vdev_queue_type_tree(vq, zio->io_type), zio);
-
-	if (shk->kstat != NULL) {
-		mutex_enter(&shk->lock);
-		kstat_waitq_enter(shk->kstat->ks_data);
-		mutex_exit(&shk->lock);
-	}
 }
 
 static void
 vdev_queue_io_remove(vdev_queue_t *vq, zio_t *zio)
 {
-	spa_t *spa = zio->io_spa;
-	spa_history_kstat_t *shk = &spa->spa_stats.io_history;
-
 	ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE);
 	avl_remove(vdev_queue_class_tree(vq, zio->io_priority), zio);
 	avl_remove(vdev_queue_type_tree(vq, zio->io_type), zio);
-
-	if (shk->kstat != NULL) {
-		mutex_enter(&shk->lock);
-		kstat_waitq_exit(shk->kstat->ks_data);
-		mutex_exit(&shk->lock);
-	}
 }
 
 static boolean_t
@@ -564,9 +544,6 @@ vdev_queue_is_interactive(zio_priority_t p)
 static void
 vdev_queue_pending_add(vdev_queue_t *vq, zio_t *zio)
 {
-	spa_t *spa = zio->io_spa;
-	spa_history_kstat_t *shk = &spa->spa_stats.io_history;
-
 	ASSERT(MUTEX_HELD(&vq->vq_lock));
 	ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE);
 	vq->vq_class[zio->io_priority].vqc_active++;
@@ -577,20 +554,11 @@ vdev_queue_pending_add(vdev_queue_t *vq, zio_t *zio)
 		vq->vq_nia_credit--;
 	}
 	avl_add(&vq->vq_active_tree, zio);
-
-	if (shk->kstat != NULL) {
-		mutex_enter(&shk->lock);
-		kstat_runq_enter(shk->kstat->ks_data);
-		mutex_exit(&shk->lock);
-	}
 }
 
 static void
 vdev_queue_pending_remove(vdev_queue_t *vq, zio_t *zio)
 {
-	spa_t *spa = zio->io_spa;
-	spa_history_kstat_t *shk = &spa->spa_stats.io_history;
-
 	ASSERT(MUTEX_HELD(&vq->vq_lock));
 	ASSERT3U(zio->io_priority, <, ZIO_PRIORITY_NUM_QUEUEABLE);
 	vq->vq_class[zio->io_priority].vqc_active--;
@@ -602,21 +570,6 @@ vdev_queue_pending_remove(vdev_queue_t *vq, zio_t *zio)
 	} else if (vq->vq_ia_active == 0)
 		vq->vq_nia_credit++;
 	avl_remove(&vq->vq_active_tree, zio);
-
-	if (shk->kstat != NULL) {
-		kstat_io_t *ksio = shk->kstat->ks_data;
-
-		mutex_enter(&shk->lock);
-		kstat_runq_exit(ksio);
-		if (zio->io_type == ZIO_TYPE_READ) {
-			ksio->reads++;
-			ksio->nread += zio->io_size;
-		} else if (zio->io_type == ZIO_TYPE_WRITE) {
-			ksio->writes++;
-			ksio->nwritten += zio->io_size;
-		}
-		mutex_exit(&shk->lock);
-	}
 }
 
 static void