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Index: head/sys/vm/uma.h
===================================================================
--- head/sys/vm/uma.h
+++ head/sys/vm/uma.h
@@ -492,7 +492,7 @@
int uma_zone_reserve_kva(uma_zone_t zone, int nitems);
/*
- * Sets a high limit on the number of items allowed in a zone
+ * Sets an upper limit on the number of items allocated from a zone
*
* Arguments:
* zone The zone to limit
@@ -504,7 +504,7 @@
int uma_zone_set_max(uma_zone_t zone, int nitems);
/*
- * Sets a high limit on the number of items allowed in zone's bucket cache
+ * Sets an upper limit on the number of items allowed in zone's caches
*
* Arguments:
* zone The zone to limit
Index: head/sys/vm/uma_core.c
===================================================================
--- head/sys/vm/uma_core.c
+++ head/sys/vm/uma_core.c
@@ -438,27 +438,6 @@
return (ubz);
}
-static struct uma_bucket_zone *
-bucket_zone_max(uma_zone_t zone, int nitems)
-{
- struct uma_bucket_zone *ubz;
- int bpcpu;
-
- bpcpu = 2;
- if ((zone->uz_flags & UMA_ZONE_FIRSTTOUCH) != 0)
- /* Count the cross-domain bucket. */
- bpcpu++;
-
- for (ubz = &bucket_zones[0]; ubz->ubz_entries != 0; ubz++)
- if (ubz->ubz_entries * bpcpu * mp_ncpus > nitems)
- break;
- if (ubz == &bucket_zones[0])
- ubz = NULL;
- else
- ubz--;
- return (ubz);
-}
-
static int
bucket_select(int size)
{
@@ -2478,10 +2457,10 @@
SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(oid), OID_AUTO,
"items", CTLFLAG_RD | CTLTYPE_U64 | CTLFLAG_MPSAFE,
zone, 0, sysctl_handle_uma_zone_items, "QU",
- "current number of allocated items if limit is set");
+ "Current number of allocated items if limit is set");
SYSCTL_ADD_U64(NULL, SYSCTL_CHILDREN(oid), OID_AUTO,
"max_items", CTLFLAG_RD, &zone->uz_max_items, 0,
- "Maximum number of cached items");
+ "Maximum number of allocated and cached items");
SYSCTL_ADD_U32(NULL, SYSCTL_CHILDREN(oid), OID_AUTO,
"sleepers", CTLFLAG_RD, &zone->uz_sleepers, 0,
"Number of threads sleeping at limit");
@@ -4570,20 +4549,19 @@
int
uma_zone_set_max(uma_zone_t zone, int nitems)
{
- struct uma_bucket_zone *ubz;
- int count;
/*
+ * If the limit is small, we may need to constrain the maximum per-CPU
+ * cache size, or disable caching entirely.
+ */
+ uma_zone_set_maxcache(zone, nitems);
+
+ /*
* XXX This can misbehave if the zone has any allocations with
* no limit and a limit is imposed. There is currently no
* way to clear a limit.
*/
ZONE_LOCK(zone);
- ubz = bucket_zone_max(zone, nitems);
- count = ubz != NULL ? ubz->ubz_entries : 0;
- zone->uz_bucket_size_max = zone->uz_bucket_size = count;
- if (zone->uz_bucket_size_min > zone->uz_bucket_size_max)
- zone->uz_bucket_size_min = zone->uz_bucket_size_max;
zone->uz_max_items = nitems;
zone->uz_flags |= UMA_ZFLAG_LIMIT;
zone_update_caches(zone);
@@ -4598,24 +4576,35 @@
void
uma_zone_set_maxcache(uma_zone_t zone, int nitems)
{
- struct uma_bucket_zone *ubz;
- int bpcpu;
+ int bpcpu, bpdom, bsize, nb;
ZONE_LOCK(zone);
- ubz = bucket_zone_max(zone, nitems);
- if (ubz != NULL) {
- bpcpu = 2;
- if ((zone->uz_flags & UMA_ZONE_FIRSTTOUCH) != 0)
- /* Count the cross-domain bucket. */
- bpcpu++;
- nitems -= ubz->ubz_entries * bpcpu * mp_ncpus;
- zone->uz_bucket_size_max = ubz->ubz_entries;
- } else {
- zone->uz_bucket_size_max = zone->uz_bucket_size = 0;
+
+ /*
+ * Compute a lower bound on the number of items that may be cached in
+ * the zone. Each CPU gets at least two buckets, and for cross-domain
+ * frees we use an additional bucket per CPU and per domain. Select the
+ * largest bucket size that does not exceed half of the requested limit,
+ * with the left over space given to the full bucket cache.
+ */
+ bpdom = 0;
+ bpcpu = 2;
+#ifdef NUMA
+ if ((zone->uz_flags & UMA_ZONE_FIRSTTOUCH) != 0 && vm_ndomains > 1) {
+ bpcpu++;
+ bpdom++;
}
+#endif
+ nb = bpcpu * mp_ncpus + bpdom * vm_ndomains;
+ bsize = nitems / nb / 2;
+ if (bsize > BUCKET_MAX)
+ bsize = BUCKET_MAX;
+ else if (bsize == 0 && nitems / nb > 0)
+ bsize = 1;
+ zone->uz_bucket_size_max = zone->uz_bucket_size = bsize;
if (zone->uz_bucket_size_min > zone->uz_bucket_size_max)
zone->uz_bucket_size_min = zone->uz_bucket_size_max;
- zone->uz_bucket_max = nitems / vm_ndomains;
+ zone->uz_bucket_max = nitems - nb * bsize;
ZONE_UNLOCK(zone);
}

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