Date: Wed, 27 Nov 2013 20:56:11 +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: r258693 - head/sys/vm Message-ID: <201311272056.rARKuBuS035883@svn.freebsd.org>
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Author: mav Date: Wed Nov 27 20:56:10 2013 New Revision: 258693 URL: http://svnweb.freebsd.org/changeset/base/258693 Log: Make UMA to not blindly force offpage slab header allocation for large (> PAGE_SIZE) zones. If zone is not multiple to PAGE_SIZE, there may be enough space for the header at the last page, so we may avoid extra header memory allocation and hash table update/lookup. ZFS creates bunch of odd-sized UMA zones (5120, 6144, 7168, 10240, 14336). This change gives good use to at least some of otherwise lost memory there. Reviewed by: avg Modified: head/sys/vm/uma_core.c Modified: head/sys/vm/uma_core.c ============================================================================== --- head/sys/vm/uma_core.c Wed Nov 27 20:20:02 2013 (r258692) +++ head/sys/vm/uma_core.c Wed Nov 27 20:56:10 2013 (r258693) @@ -1318,6 +1318,7 @@ keg_small_init(uma_keg_t keg) static void keg_large_init(uma_keg_t keg) { + u_int shsize; KASSERT(keg != NULL, ("Keg is null in keg_large_init")); KASSERT((keg->uk_flags & UMA_ZFLAG_CACHEONLY) == 0, @@ -1334,8 +1335,21 @@ keg_large_init(uma_keg_t keg) if (keg->uk_flags & UMA_ZFLAG_INTERNAL) return; - keg->uk_flags |= UMA_ZONE_OFFPAGE; - if ((keg->uk_flags & UMA_ZONE_VTOSLAB) == 0) + /* Check whether we have enough space to not do OFFPAGE. */ + if ((keg->uk_flags & UMA_ZONE_OFFPAGE) == 0) { + shsize = sizeof(struct uma_slab); + if (keg->uk_flags & UMA_ZONE_REFCNT) + shsize += keg->uk_ipers * sizeof(uint32_t); + if (shsize & UMA_ALIGN_PTR) + shsize = (shsize & ~UMA_ALIGN_PTR) + + (UMA_ALIGN_PTR + 1); + + if ((PAGE_SIZE * keg->uk_ppera) - keg->uk_rsize < shsize) + keg->uk_flags |= UMA_ZONE_OFFPAGE; + } + + if ((keg->uk_flags & UMA_ZONE_OFFPAGE) && + (keg->uk_flags & UMA_ZONE_VTOSLAB) == 0) keg->uk_flags |= UMA_ZONE_HASH; }
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