Author: mav
Date: Wed May 22 18:43:48 2019
New Revision: 348117
URL: https://svnweb.freebsd.org/changeset/base/348117
Log:
Allocate buffers smaller then ABD chunk size as linear.
This allows to reduce memory waste by letting UMA to put multiple small
buffers into one memory page slab. The page sharing means that UMA
may not be able to free memory page when some of buffers are freed, but
alternatively memory used by that buffer would just be wasted from the
beginning.
This change follows alike change in ZoL, but unlike Linux (according to
my understanding of it from comments) FreeBSD never shares slabs bigger
then one memory page, so this should be even less invasive then there.
MFC after: 2 weeks
Sponsored by: iXsystems, Inc.
Modified:
head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c
Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c
==============================================================================
--- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c Wed May 22
17:42:22 2019 (r348116)
+++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/abd.c Wed May 22
18:43:48 2019 (r348117)
@@ -290,7 +290,7 @@ abd_free_struct(abd_t *abd)
abd_t *
abd_alloc(size_t size, boolean_t is_metadata)
{
- if (!zfs_abd_scatter_enabled)
+ if (!zfs_abd_scatter_enabled || size <= zfs_abd_chunk_size)
return (abd_alloc_linear(size, is_metadata));
VERIFY3U(size, <=, SPA_MAXBLOCKSIZE);
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