From fc7546777ba15a7fff651cd803bf521f592d8379 Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Tue, 25 Jun 2019 15:03:38 -0400 Subject: 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. Reviewed by: Sean Eric Fagan Reviewed by: Matt Ahrens Reviewed by: Brian Behlendorf Signed-off-by: Alexander Motin Closes #8909 --- module/zfs/dmu_objset.c | 19 ++++++++++++++----- module/zfs/multilist.c | 22 ++++++++++++++++++++++ 2 files changed, 36 insertions(+), 5 deletions(-) (limited to 'module/zfs') diff --git a/module/zfs/dmu_objset.c b/module/zfs/dmu_objset.c index 4091ac355..8b55469a5 100644 --- a/module/zfs/dmu_objset.c +++ b/module/zfs/dmu_objset.c @@ -1598,6 +1598,8 @@ 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; @@ -1686,10 +1688,13 @@ 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, @@ -1992,6 +1997,8 @@ 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; @@ -2024,8 +2031,10 @@ dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx) 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; diff --git a/module/zfs/multilist.c b/module/zfs/multilist.c index 2a594c56c..b74ee0f06 100644 --- a/module/zfs/multilist.c +++ b/module/zfs/multilist.c @@ -363,6 +363,28 @@ multilist_sublist_remove(multilist_sublist_t *mls, void *obj) 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) { -- cgit v1.2.3