From fadd0c4da1e2ccd6014800d8b1a0fd117dd323e8 Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Thu, 25 Jul 2013 10:39:31 -0700 Subject: [PATCH] Evict meta data from ghost lists + l2arc headers When the meta limit is exceeded the ARC evicts some meta data buffers from the mfu+mru lists. Unfortunately, for meta data heavy workloads it's possible for these buffers to accumulate on the ghost lists if arc_c doesn't exceed arc_size. To handle this case arc_adjust_meta() has been entended to explicitly evict meta data buffers from the ghost lists in proportion to what was evicted from the mfu+mru lists. If this is insufficient we request that the VFS release some inodes and dentries. This will result in the release of some dnodes which are counted as 'other' metadata. Signed-off-by: Brian Behlendorf --- module/zfs/arc.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/module/zfs/arc.c b/module/zfs/arc.c index ce4a0239c..32ad80bcb 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -2104,8 +2104,9 @@ arc_do_user_evicts(void) void arc_adjust_meta(int64_t adjustment, boolean_t may_prune) { - int64_t delta; + int64_t delta, tmp = adjustment; + /* Evict MRU+MFU meta data to ghost lists */ if (adjustment > 0 && arc_mru->arcs_lsize[ARC_BUFC_METADATA] > 0) { delta = MIN(arc_mru->arcs_lsize[ARC_BUFC_METADATA], adjustment); arc_evict(arc_mru, 0, delta, FALSE, ARC_BUFC_METADATA); @@ -2115,9 +2116,24 @@ arc_adjust_meta(int64_t adjustment, boolean_t may_prune) if (adjustment > 0 && arc_mfu->arcs_lsize[ARC_BUFC_METADATA] > 0) { delta = MIN(arc_mfu->arcs_lsize[ARC_BUFC_METADATA], adjustment); arc_evict(arc_mfu, 0, delta, FALSE, ARC_BUFC_METADATA); + } + + /* Evict ghost MRU+MFU meta data */ + adjustment = tmp; + + if (adjustment > 0 && arc_mru_ghost->arcs_size > 0) { + delta = MIN(arc_mru_ghost->arcs_size, adjustment); + arc_evict_ghost(arc_mru_ghost, 0, delta, ARC_BUFC_METADATA); adjustment -= delta; } + if (adjustment > 0 && arc_mfu_ghost->arcs_size > 0) { + delta = MIN(arc_mfu_ghost->arcs_size, adjustment); + arc_evict_ghost(arc_mfu_ghost, 0, delta, ARC_BUFC_METADATA); + adjustment -= delta; + } + + /* Request the VFS release some meta data */ if (may_prune && (adjustment > 0) && (arc_meta_used > arc_meta_limit)) arc_do_user_prune(zfs_arc_meta_prune); }