Date: Wed, 22 Oct 2014 04:09:47 +0000 (UTC) From: Bryan Venteicher <bryanv@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r273451 - stable/10/sys/vm Message-ID: <201410220409.s9M49lWH093815@svn.freebsd.org>
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Author: bryanv Date: Wed Oct 22 04:09:47 2014 New Revision: 273451 URL: https://svnweb.freebsd.org/changeset/base/273451 Log: MFC r272573: Change the UMA mutex into a rwlock Acquire the lock in read mode when just needed to ensure the stability of the keg list. The UMA lock may be held for a long time (relatively speaking) in uma_reclaim() on machines with lots of zones/kegs. If the uma_timeout() would fire during that period, subsequent callouts on that CPU may be significantly delayed. Modified: stable/10/sys/vm/uma_core.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/vm/uma_core.c ============================================================================== --- stable/10/sys/vm/uma_core.c Wed Oct 22 04:01:27 2014 (r273450) +++ stable/10/sys/vm/uma_core.c Wed Oct 22 04:09:47 2014 (r273451) @@ -135,8 +135,8 @@ static LIST_HEAD(,uma_keg) uma_kegs = LI static LIST_HEAD(,uma_zone) uma_cachezones = LIST_HEAD_INITIALIZER(uma_cachezones); -/* This mutex protects the keg list */ -static struct mtx_padalign uma_mtx; +/* This RW lock protects the keg list */ +static struct rwlock_padalign uma_rwlock; /* Linked list of boot time pages */ static LIST_HEAD(,uma_slab) uma_boot_pages = @@ -905,7 +905,7 @@ zone_drain_wait(uma_zone_t zone, int wai ZONE_UNLOCK(zone); /* * The DRAINING flag protects us from being freed while - * we're running. Normally the uma_mtx would protect us but we + * we're running. Normally the uma_rwlock would protect us but we * must be able to release and acquire the right lock for each keg. */ zone_foreach_keg(zone, &keg_drain); @@ -1541,9 +1541,9 @@ keg_ctor(void *mem, int size, void *udat LIST_INSERT_HEAD(&keg->uk_zones, zone, uz_link); - mtx_lock(&uma_mtx); + rw_wlock(&uma_rwlock); LIST_INSERT_HEAD(&uma_kegs, keg, uk_link); - mtx_unlock(&uma_mtx); + rw_wunlock(&uma_rwlock); return (0); } @@ -1593,9 +1593,9 @@ zone_ctor(void *mem, int size, void *uda zone->uz_release = arg->release; zone->uz_arg = arg->arg; zone->uz_lockptr = &zone->uz_lock; - mtx_lock(&uma_mtx); + rw_wlock(&uma_rwlock); LIST_INSERT_HEAD(&uma_cachezones, zone, uz_link); - mtx_unlock(&uma_mtx); + rw_wunlock(&uma_rwlock); goto out; } @@ -1612,7 +1612,7 @@ zone_ctor(void *mem, int size, void *uda zone->uz_fini = arg->fini; zone->uz_lockptr = &keg->uk_lock; zone->uz_flags |= UMA_ZONE_SECONDARY; - mtx_lock(&uma_mtx); + rw_wlock(&uma_rwlock); ZONE_LOCK(zone); LIST_FOREACH(z, &keg->uk_zones, uz_link) { if (LIST_NEXT(z, uz_link) == NULL) { @@ -1621,7 +1621,7 @@ zone_ctor(void *mem, int size, void *uda } } ZONE_UNLOCK(zone); - mtx_unlock(&uma_mtx); + rw_wunlock(&uma_rwlock); } else if (keg == NULL) { if ((keg = uma_kcreate(zone, arg->size, arg->uminit, arg->fini, arg->align, arg->flags)) == NULL) @@ -1719,9 +1719,9 @@ zone_dtor(void *arg, int size, void *uda if (!(zone->uz_flags & UMA_ZFLAG_INTERNAL)) cache_drain(zone); - mtx_lock(&uma_mtx); + rw_wlock(&uma_rwlock); LIST_REMOVE(zone, uz_link); - mtx_unlock(&uma_mtx); + rw_wunlock(&uma_rwlock); /* * XXX there are some races here where * the zone can be drained but zone lock @@ -1743,9 +1743,9 @@ zone_dtor(void *arg, int size, void *uda * We only destroy kegs from non secondary zones. */ if (keg != NULL && (zone->uz_flags & UMA_ZONE_SECONDARY) == 0) { - mtx_lock(&uma_mtx); + rw_wlock(&uma_rwlock); LIST_REMOVE(keg, uk_link); - mtx_unlock(&uma_mtx); + rw_wunlock(&uma_rwlock); zone_free_item(kegs, keg, NULL, SKIP_NONE); } ZONE_LOCK_FINI(zone); @@ -1767,12 +1767,12 @@ zone_foreach(void (*zfunc)(uma_zone_t)) uma_keg_t keg; uma_zone_t zone; - mtx_lock(&uma_mtx); + rw_rlock(&uma_rwlock); LIST_FOREACH(keg, &uma_kegs, uk_link) { LIST_FOREACH(zone, &keg->uk_zones, uz_link) zfunc(zone); } - mtx_unlock(&uma_mtx); + rw_runlock(&uma_rwlock); } /* Public functions */ @@ -1788,7 +1788,7 @@ uma_startup(void *bootmem, int boot_page #ifdef UMA_DEBUG printf("Creating uma keg headers zone and keg.\n"); #endif - mtx_init(&uma_mtx, "UMA lock", NULL, MTX_DEF); + rw_init(&uma_rwlock, "UMA lock"); /* "manually" create the initial zone */ memset(&args, 0, sizeof(args)); @@ -3363,12 +3363,12 @@ sysctl_vm_zone_count(SYSCTL_HANDLER_ARGS int count; count = 0; - mtx_lock(&uma_mtx); + rw_rlock(&uma_rwlock); LIST_FOREACH(kz, &uma_kegs, uk_link) { LIST_FOREACH(z, &kz->uk_zones, uz_link) count++; } - mtx_unlock(&uma_mtx); + rw_runlock(&uma_rwlock); return (sysctl_handle_int(oidp, &count, 0, req)); } @@ -3393,7 +3393,7 @@ sysctl_vm_zone_stats(SYSCTL_HANDLER_ARGS sbuf_new_for_sysctl(&sbuf, NULL, 128, req); count = 0; - mtx_lock(&uma_mtx); + rw_rlock(&uma_rwlock); LIST_FOREACH(kz, &uma_kegs, uk_link) { LIST_FOREACH(z, &kz->uk_zones, uz_link) count++; @@ -3469,7 +3469,7 @@ skip: ZONE_UNLOCK(z); } } - mtx_unlock(&uma_mtx); + rw_runlock(&uma_rwlock); error = sbuf_finish(&sbuf); sbuf_delete(&sbuf); return (error);
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