Date: Wed, 22 May 2019 18:43:48 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r348117 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <201905221843.x4MIhmh1012837@repo.freebsd.org>
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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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