Date: Tue, 4 Feb 2020 22:40:46 +0000 (UTC) From: Ryan Libby <rlibby@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r357550 - head/sys/vm Message-ID: <202002042240.014MekRs068957@repo.freebsd.org>
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Author: rlibby Date: Tue Feb 4 22:40:45 2020 New Revision: 357550 URL: https://svnweb.freebsd.org/changeset/base/357550 Log: uma: multipage chicken switch Add a switch to allow disabling multipage slabs, in order to facilitate measuring memory usage and performance effects. The tunable vm.debug.uma_multipage_slabs defaults to 1 and can be set to 0 to disable. The name may change soon. Reviewed by: markj (previous version) Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D23487 Modified: head/sys/vm/uma_core.c Modified: head/sys/vm/uma_core.c ============================================================================== --- head/sys/vm/uma_core.c Tue Feb 4 22:40:34 2020 (r357549) +++ head/sys/vm/uma_core.c Tue Feb 4 22:40:45 2020 (r357550) @@ -323,6 +323,9 @@ static int sysctl_handle_uma_zone_items(SYSCTL_HANDLER static uint64_t uma_zone_get_allocs(uma_zone_t zone); +static SYSCTL_NODE(_vm, OID_AUTO, debug, CTLFLAG_RD, 0, + "Memory allocation debugging"); + #ifdef INVARIANTS static uint64_t uma_keg_get_allocs(uma_keg_t zone); static inline struct noslabbits *slab_dbg_bits(uma_slab_t slab, uma_keg_t keg); @@ -332,9 +335,6 @@ static bool uma_dbg_zskip(uma_zone_t zone, void *mem); static void uma_dbg_free(uma_zone_t zone, uma_slab_t slab, void *item); static void uma_dbg_alloc(uma_zone_t zone, uma_slab_t slab, void *item); -static SYSCTL_NODE(_vm, OID_AUTO, debug, CTLFLAG_RD, 0, - "Memory allocation debugging"); - static u_int dbg_divisor = 1; SYSCTL_UINT(_vm_debug, OID_AUTO, divisor, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &dbg_divisor, 0, @@ -362,6 +362,12 @@ static int zone_warnings = 1; SYSCTL_INT(_vm, OID_AUTO, zone_warnings, CTLFLAG_RWTUN, &zone_warnings, 0, "Warn when UMA zones becomes full"); +static int multipage_slabs = 1; +TUNABLE_INT("vm.debug.uma_multipage_slabs", &multipage_slabs); +SYSCTL_INT(_vm_debug, OID_AUTO, uma_multipage_slabs, + CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &multipage_slabs, 0, + "UMA may choose larger slab sizes for better efficiency"); + /* * Select the slab zone for an offpage slab with the given maximum item count. */ @@ -1993,7 +1999,7 @@ keg_layout(uma_keg_t keg) break; } - if (kl.eff >= UMA_MIN_EFF || + if (kl.eff >= UMA_MIN_EFF || !multipage_slabs || slabsize >= SLAB_MAX_SETSIZE * rsize || (keg->uk_flags & (UMA_ZONE_PCPU | UMA_ZONE_CONTIG)) != 0) break;
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