Author: mav
Date: Tue Jun 25 18:35:23 2019
New Revision: 349381
URL: https://svnweb.freebsd.org/changeset/base/349381
Log:
Avoid extra taskq_dispatch() calls by DMU.
DMU sync code calls taskq_dispatch() for each sublist of os_dirty_dnodes
and os_synced_dnodes. Since the number of sublists by default is equal
to number of CPUs, it will dispatch equal, potentially large, number of
tasks, waking up many CPUs to handle them, even if only one or few of
sublists actually have any work to do.
This change adds check for empty sublists to avoid this.
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/multilist.c
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/multilist.h
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c Tue Jun
25 18:13:39 2019 (r349380)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c Tue Jun
25 18:35:23 2019 (r349381)
@@ -1334,6 +1334,8 @@ dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx
zio_t *zio;
list_t *list;
dbuf_dirty_record_t *dr;
+ int num_sublists;
+ multilist_t *ml;
blkptr_t *blkptr_copy = kmem_alloc(sizeof (*os->os_rootbp), KM_SLEEP);
*blkptr_copy = *os->os_rootbp;
@@ -1402,10 +1404,13 @@ dmu_objset_sync(objset_t *os, zio_t *pio, dmu_tx_t *tx
}
}
- for (int i = 0;
- i < multilist_get_num_sublists(os->os_dirty_dnodes[txgoff]); i++) {
+ ml = os->os_dirty_dnodes[txgoff];
+ num_sublists = multilist_get_num_sublists(ml);
+ for (int i = 0; i < num_sublists; i++) {
+ if (multilist_sublist_is_empty_idx(ml, i))
+ continue;
sync_dnodes_arg_t *sda = kmem_alloc(sizeof (*sda), KM_SLEEP);
- sda->sda_list = os->os_dirty_dnodes[txgoff];
+ sda->sda_list = ml;
sda->sda_sublist_idx = i;
sda->sda_tx = tx;
(void) taskq_dispatch(dmu_objset_pool(os)->dp_sync_taskq,
@@ -1619,6 +1624,8 @@ userquota_updates_task(void *arg)
void
dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx)
{
+ int num_sublists;
+
if (!dmu_objset_userused_enabled(os))
return;
@@ -1632,8 +1639,10 @@ dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t
DMU_OT_USERGROUP_USED, DMU_OT_NONE, 0, tx));
}
- for (int i = 0;
- i < multilist_get_num_sublists(os->os_synced_dnodes); i++) {
+ num_sublists = multilist_get_num_sublists(os->os_synced_dnodes);
+ for (int i = 0; i < num_sublists; i++) {
+ if (multilist_sublist_is_empty_idx(os->os_synced_dnodes, i))
+ continue;
userquota_updates_arg_t *uua =
kmem_alloc(sizeof (*uua), KM_SLEEP);
uua->uua_os = os;
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/multilist.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/multilist.c Tue Jun
25 18:13:39 2019 (r349380)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/multilist.c Tue Jun
25 18:35:23 2019 (r349381)
@@ -360,6 +360,28 @@ multilist_sublist_remove(multilist_sublist_t *mls, voi
list_remove(&mls->mls_list, obj);
}
+int
+multilist_sublist_is_empty(multilist_sublist_t *mls)
+{
+ ASSERT(MUTEX_HELD(&mls->mls_lock));
+ return (list_is_empty(&mls->mls_list));
+}
+
+int
+multilist_sublist_is_empty_idx(multilist_t *ml, unsigned int sublist_idx)
+{
+ multilist_sublist_t *mls;
+ int empty;
+
+ ASSERT3U(sublist_idx, <, ml->ml_num_sublists);
+ mls = &ml->ml_sublists[sublist_idx];
+ ASSERT(!MUTEX_HELD(&mls->mls_lock));
+ mutex_enter(&mls->mls_lock);
+ empty = list_is_empty(&mls->mls_list);
+ mutex_exit(&mls->mls_lock);
+ return (empty);
+}
+
void *
multilist_sublist_head(multilist_sublist_t *mls)
{
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/multilist.h
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/multilist.h Tue Jun
25 18:13:39 2019 (r349380)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/multilist.h Tue Jun
25 18:35:23 2019 (r349381)
@@ -89,6 +89,8 @@ void multilist_sublist_insert_head(multilist_sublist_t
void multilist_sublist_insert_tail(multilist_sublist_t *, void *);
void multilist_sublist_move_forward(multilist_sublist_t *mls, void *obj);
void multilist_sublist_remove(multilist_sublist_t *, void *);
+int multilist_sublist_is_empty(multilist_sublist_t *);
+int multilist_sublist_is_empty_idx(multilist_t *, unsigned int);
void *multilist_sublist_head(multilist_sublist_t *);
void *multilist_sublist_tail(multilist_sublist_t *);
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