svn commit: r356563 - head/sys/vm
Mark Johnston
markj at FreeBSD.org
Thu Jan 9 19:17:43 UTC 2020
Author: markj
Date: Thu Jan 9 19:17:42 2020
New Revision: 356563
URL: https://svnweb.freebsd.org/changeset/base/356563
Log:
UMA: Don't destroy zones after the system shutdown process starts.
Some kernel subsystems, notably ZFS, will destroy UMA zones from a
shutdown eventhandler. This causes the zone to be drained. For slabs
that are mapped into KVA this can be very expensive and so it needlessly
delays the shutdown process.
Add a new state to the "booted" variable, BOOT_SHUTDOWN. Once
kern_reboot() starts invoking shutdown handlers, turn uma_zdestroy()
into a no-op, provided that the zone does not have a custom finalization
routine.
PR: 242427
Reviewed by: jeff, kib, rlibby
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D23066
Modified:
head/sys/vm/uma_core.c
Modified: head/sys/vm/uma_core.c
==============================================================================
--- head/sys/vm/uma_core.c Thu Jan 9 19:13:09 2020 (r356562)
+++ head/sys/vm/uma_core.c Thu Jan 9 19:17:42 2020 (r356563)
@@ -158,8 +158,14 @@ SYSCTL_ULONG(_vm, OID_AUTO, uma_kmem_total, CTLFLAG_RD
"UMA kernel memory usage");
/* Is the VM done starting up? */
-static enum { BOOT_COLD = 0, BOOT_STRAPPED, BOOT_PAGEALLOC, BOOT_BUCKETS,
- BOOT_RUNNING } booted = BOOT_COLD;
+static enum {
+ BOOT_COLD,
+ BOOT_STRAPPED,
+ BOOT_PAGEALLOC,
+ BOOT_BUCKETS,
+ BOOT_RUNNING,
+ BOOT_SHUTDOWN,
+} booted = BOOT_COLD;
/*
* This is the handle used to schedule events that need to happen
@@ -265,6 +271,7 @@ static int hash_expand(struct uma_hash *, struct uma_h
static void hash_free(struct uma_hash *hash);
static void uma_timeout(void *);
static void uma_startup3(void);
+static void uma_shutdown(void);
static void *zone_alloc_item(uma_zone_t, void *, int, int);
static void zone_free_item(uma_zone_t, void *, void *, enum zfreeskip);
static int zone_alloc_limit(uma_zone_t zone, int count, int flags);
@@ -1408,8 +1415,7 @@ startup_alloc(uma_zone_t zone, vm_size_t bytes, int do
case BOOT_PAGEALLOC:
if (keg->uk_ppera > 1)
break;
- case BOOT_BUCKETS:
- case BOOT_RUNNING:
+ default:
#ifdef UMA_MD_SMALL_ALLOC
keg->uk_allocf = (keg->uk_ppera > 1) ?
page_alloc : uma_small_alloc;
@@ -2337,7 +2343,7 @@ zone_ctor(void *mem, int size, void *udata, int flags)
(UMA_ZONE_INHERIT | UMA_ZFLAG_INHERIT));
out:
- if (__predict_true(booted == BOOT_RUNNING)) {
+ if (__predict_true(booted >= BOOT_RUNNING)) {
zone_alloc_counters(zone, NULL);
zone_alloc_sysctl(zone, NULL);
} else {
@@ -2465,7 +2471,7 @@ zone_foreach(void (*zfunc)(uma_zone_t, void *arg), voi
* threaded, so locking isn't needed. Startup functions
* are allowed to use M_WAITOK.
*/
- if (__predict_true(booted == BOOT_RUNNING))
+ if (__predict_true(booted >= BOOT_RUNNING))
rw_rlock(&uma_rwlock);
LIST_FOREACH(keg, &uma_kegs, uk_link) {
LIST_FOREACH(zone, &keg->uk_zones, uz_link)
@@ -2473,7 +2479,7 @@ zone_foreach(void (*zfunc)(uma_zone_t, void *arg), voi
}
LIST_FOREACH(zone, &uma_cachezones, uz_link)
zfunc(zone, arg);
- if (__predict_true(booted == BOOT_RUNNING))
+ if (__predict_true(booted >= BOOT_RUNNING))
rw_runlock(&uma_rwlock);
}
@@ -2635,10 +2641,6 @@ uma_startup2(void)
bucket_enable();
}
-/*
- * Initialize our callout handle
- *
- */
static void
uma_startup3(void)
{
@@ -2653,8 +2655,18 @@ uma_startup3(void)
callout_init(&uma_callout, 1);
callout_reset(&uma_callout, UMA_TIMEOUT * hz, uma_timeout, NULL);
booted = BOOT_RUNNING;
+
+ EVENTHANDLER_REGISTER(shutdown_post_sync, uma_shutdown, NULL,
+ EVENTHANDLER_PRI_FIRST);
}
+static void
+uma_shutdown(void)
+{
+
+ booted = BOOT_SHUTDOWN;
+}
+
static uma_keg_t
uma_kcreate(uma_zone_t zone, size_t size, uma_init uminit, uma_fini fini,
int align, uint32_t flags)
@@ -2796,6 +2808,13 @@ void
uma_zdestroy(uma_zone_t zone)
{
+ /*
+ * Large slabs are expensive to reclaim, so don't bother doing
+ * unnecessary work if we're shutting down.
+ */
+ if (booted == BOOT_SHUTDOWN &&
+ zone->uz_fini == NULL && zone->uz_release == zone_release)
+ return;
sx_slock(&uma_reclaim_lock);
zone_free_item(zones, zone, NULL, SKIP_NONE);
sx_sunlock(&uma_reclaim_lock);
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