Fix UMA's first-touch policy on systems with empty domains.
Suppose a thread is running on a CPU in a NUMA domain with no physical RAM. When an item is freed to a first-touch zone, it ends up in the cross-domain bucket. When the bucket is full, it gets placed in another domain's bucket queue. However, when allocating an item, UMA will always go to the keg upon a per-CPU cache miss because the empty domain's bucket queue will always be empty. This means that a non-empty domain's bucket queues can grow very rapidly on such systems. For example, it can easily cause mbuf allocation failures when the zone limit is reached. Change cache_alloc() to follow a round-robin policy when running on an empty domain. Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D25355
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=362740
@ -3398,7 +3398,7 @@ static __noinline bool
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cache_alloc(uma_zone_t zone, uma_cache_t cache, void *udata, int flags)
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cache_alloc(uma_zone_t zone, uma_cache_t cache, void *udata, int flags)
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{
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{
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uma_bucket_t bucket;
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uma_bucket_t bucket;
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int domain;
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int curdomain, domain;
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bool new;
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bool new;
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CRITICAL_ASSERT(curthread);
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CRITICAL_ASSERT(curthread);
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@ -3445,7 +3445,8 @@ cache_alloc(uma_zone_t zone, uma_cache_t cache, void *udata, int flags)
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* the critical section.
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* the critical section.
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*/
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*/
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domain = PCPU_GET(domain);
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domain = PCPU_GET(domain);
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if ((cache_uz_flags(cache) & UMA_ZONE_ROUNDROBIN) != 0)
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if ((cache_uz_flags(cache) & UMA_ZONE_ROUNDROBIN) != 0 ||
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VM_DOMAIN_EMPTY(domain))
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domain = zone_domain_highest(zone, domain);
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domain = zone_domain_highest(zone, domain);
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bucket = cache_fetch_bucket(zone, cache, domain);
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bucket = cache_fetch_bucket(zone, cache, domain);
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if (bucket == NULL) {
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if (bucket == NULL) {
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@ -3470,7 +3471,8 @@ cache_alloc(uma_zone_t zone, uma_cache_t cache, void *udata, int flags)
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cache = &zone->uz_cpu[curcpu];
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cache = &zone->uz_cpu[curcpu];
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if (cache->uc_allocbucket.ucb_bucket == NULL &&
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if (cache->uc_allocbucket.ucb_bucket == NULL &&
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((cache_uz_flags(cache) & UMA_ZONE_FIRSTTOUCH) == 0 ||
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((cache_uz_flags(cache) & UMA_ZONE_FIRSTTOUCH) == 0 ||
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domain == PCPU_GET(domain))) {
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(curdomain = PCPU_GET(domain)) == domain ||
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VM_DOMAIN_EMPTY(curdomain))) {
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if (new)
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if (new)
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atomic_add_long(&ZDOM_GET(zone, domain)->uzd_imax,
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atomic_add_long(&ZDOM_GET(zone, domain)->uzd_imax,
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bucket->ub_cnt);
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bucket->ub_cnt);
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@ -3877,7 +3879,7 @@ zone_alloc_bucket(uma_zone_t zone, void *udata, int domain, int flags)
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/* Avoid allocs targeting empty domains. */
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/* Avoid allocs targeting empty domains. */
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if (domain != UMA_ANYDOMAIN && VM_DOMAIN_EMPTY(domain))
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if (domain != UMA_ANYDOMAIN && VM_DOMAIN_EMPTY(domain))
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domain = UMA_ANYDOMAIN;
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domain = UMA_ANYDOMAIN;
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if ((zone->uz_flags & UMA_ZONE_ROUNDROBIN) != 0)
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else if ((zone->uz_flags & UMA_ZONE_ROUNDROBIN) != 0)
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domain = UMA_ANYDOMAIN;
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domain = UMA_ANYDOMAIN;
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if (zone->uz_max_items > 0)
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if (zone->uz_max_items > 0)
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