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| author | Tejun Heo <tj@kernel.org> | 2017-02-22 15:41:30 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-02-22 16:41:27 -0800 |
| commit | 01fb58bcba63f8fba37581c24c99e9a515dd0335 (patch) | |
| tree | 475ebac1b656204783280c52acf315dfd3caea03 /mm/slab.h | |
| parent | c9fc586403e7c85eee06b2d5dea14ce71c00fcd8 (diff) | |
| download | linux-01fb58bcba63f8fba37581c24c99e9a515dd0335.tar.gz linux-01fb58bcba63f8fba37581c24c99e9a515dd0335.tar.bz2 linux-01fb58bcba63f8fba37581c24c99e9a515dd0335.zip | |
slab: remove synchronous synchronize_sched() from memcg cache deactivation path
With kmem cgroup support enabled, kmem_caches can be created and
destroyed frequently and a great number of near empty kmem_caches can
accumulate if there are a lot of transient cgroups and the system is not
under memory pressure. When memory reclaim starts under such
conditions, it can lead to consecutive deactivation and destruction of
many kmem_caches, easily hundreds of thousands on moderately large
systems, exposing scalability issues in the current slab management
code. This is one of the patches to address the issue.
slub uses synchronize_sched() to deactivate a memcg cache.
synchronize_sched() is an expensive and slow operation and doesn't scale
when a huge number of caches are destroyed back-to-back. While there
used to be a simple batching mechanism, the batching was too restricted
to be helpful.
This patch implements slab_deactivate_memcg_cache_rcu_sched() which slub
can use to schedule sched RCU callback instead of performing
synchronize_sched() synchronously while holding cgroup_mutex. While
this adds online cpus, mems and slab_mutex operations, operating on
these locks back-to-back from the same kworker, which is what's gonna
happen when there are many to deactivate, isn't expensive at all and
this gets rid of the scalability problem completely.
Link: http://lkml.kernel.org/r/20170117235411.9408-9-tj@kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jay Vana <jsvana@fb.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab.h')
| -rw-r--r-- | mm/slab.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/slab.h b/mm/slab.h index 7bff1ee513c2..65e7c3fcac72 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -307,6 +307,8 @@ static __always_inline void memcg_uncharge_slab(struct page *page, int order, extern void slab_init_memcg_params(struct kmem_cache *); extern void memcg_link_cache(struct kmem_cache *s); +extern void slab_deactivate_memcg_cache_rcu_sched(struct kmem_cache *s, + void (*deact_fn)(struct kmem_cache *)); #else /* CONFIG_MEMCG && !CONFIG_SLOB */ |