From 800d59d5771806459a23f10f3c9ee8f2d178b9ed Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Wed, 29 May 2024 11:53:31 -0400 Subject: [PATCH] Some improvements to metaslabs eviction - Add old eviction for special and dedup metaslab classes. Those vdevs may be potentially big and fragmented with large metaslabs, while their asynchronous write pattern is not really different from normal class. It seems an omission to not evict old metaslabs from them. - If we have metaslab preload enabled, which means we are not too low on memory, do not evict active metaslabs even if they are not used for some time. Eviction of active metaslabs means we won't be able to write anything until we load them, that may take some time, that is straight opposite to metaslab preload goals. For small systems the memory saving should be less important after recent reduction in number of allocators and so open metaslabs. Reviewed-by: Brian Behlendorf Signed-off-by: Alexander Motin Sponsored by: iXsystems, Inc. Closes #16214 --- module/zfs/metaslab.c | 7 +++++-- module/zfs/spa.c | 3 +++ 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/module/zfs/metaslab.c b/module/zfs/metaslab.c index cb004930d..7170b5eef 100644 --- a/module/zfs/metaslab.c +++ b/module/zfs/metaslab.c @@ -638,6 +638,7 @@ void metaslab_class_evict_old(metaslab_class_t *mc, uint64_t txg) { multilist_t *ml = &mc->mc_metaslab_txg_list; + hrtime_t now = gethrtime(); for (int i = 0; i < multilist_get_num_sublists(ml); i++) { multilist_sublist_t *mls = multilist_sublist_lock_idx(ml, i); metaslab_t *msp = multilist_sublist_head(mls); @@ -661,8 +662,10 @@ metaslab_class_evict_old(metaslab_class_t *mc, uint64_t txg) multilist_sublist_unlock(mls); if (txg > msp->ms_selected_txg + metaslab_unload_delay && - gethrtime() > msp->ms_selected_time + - (uint64_t)MSEC2NSEC(metaslab_unload_delay_ms)) { + now > msp->ms_selected_time + + MSEC2NSEC(metaslab_unload_delay_ms) && + (msp->ms_allocator == -1 || + !metaslab_preload_enabled)) { metaslab_evict(msp, txg); } else { /* diff --git a/module/zfs/spa.c b/module/zfs/spa.c index 412f883e9..638572996 100644 --- a/module/zfs/spa.c +++ b/module/zfs/spa.c @@ -10168,6 +10168,9 @@ spa_sync(spa_t *spa, uint64_t txg) metaslab_class_evict_old(spa->spa_normal_class, txg); metaslab_class_evict_old(spa->spa_log_class, txg); + /* spa_embedded_log_class has only one metaslab per vdev. */ + metaslab_class_evict_old(spa->spa_special_class, txg); + metaslab_class_evict_old(spa->spa_dedup_class, txg); spa_sync_close_syncing_log_sm(spa);