From f7c1db6366947d879d0103a0970d22d9663ef20e Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Thu, 21 Mar 2024 18:42:21 -0400 Subject: [PATCH] BRT: Change brt_pending_tree sorting order It does not look important how exactly brt_pending_tree is sorted. When cloning large file, it is quite likely that all of its blocks have identical physical birth times, so comparing them first does not provide useful entropy, while accesses additional cache line. In most cases combination of vdev and offset provides unique result and physical birth time comparison is not even needed. Meanwhile, when traversing the tree inside brt_pending_apply(), it can be beneficial for dbuf cache and CPU cache hits to group processing by vdev and so by the per-VDEV BRT ZAPs. Reviewed-by: Rob Norris Reviewed-by: Brian Atkinson Reviewed-by: Brian Behlendorf Signed-off-by: Alexander Motin Sponsored by: iXsystems, Inc. Closes #15954 --- module/zfs/brt.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/module/zfs/brt.c b/module/zfs/brt.c index 225ddaca1e..3d565cd139 100644 --- a/module/zfs/brt.c +++ b/module/zfs/brt.c @@ -1420,13 +1420,14 @@ brt_pending_entry_compare(const void *x1, const void *x2) const blkptr_t *bp1 = &bpe1->bpe_bp, *bp2 = &bpe2->bpe_bp; int cmp; - cmp = TREE_CMP(BP_PHYSICAL_BIRTH(bp1), BP_PHYSICAL_BIRTH(bp2)); + cmp = TREE_CMP(DVA_GET_VDEV(&bp1->blk_dva[0]), + DVA_GET_VDEV(&bp2->blk_dva[0])); if (cmp == 0) { - cmp = TREE_CMP(DVA_GET_VDEV(&bp1->blk_dva[0]), - DVA_GET_VDEV(&bp2->blk_dva[0])); - if (cmp == 0) { - cmp = TREE_CMP(DVA_GET_OFFSET(&bp1->blk_dva[0]), - DVA_GET_OFFSET(&bp2->blk_dva[0])); + cmp = TREE_CMP(DVA_GET_OFFSET(&bp1->blk_dva[0]), + DVA_GET_OFFSET(&bp2->blk_dva[0])); + if (unlikely(cmp == 0)) { + cmp = TREE_CMP(BP_PHYSICAL_BIRTH(bp1), + BP_PHYSICAL_BIRTH(bp2)); } }