Commit d1a05b69 authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds

memcg: do not try to drain per-cpu caches without pages

drain_all_stock_async tries to optimize a work to be done on the work
queue by excluding any work for the current CPU because it assumes that
the context we are called from already tried to charge from that cache
and it's failed so it must be empty already.

While the assumption is correct we can optimize it even more by checking
the current number of pages in the cache.  This will also reduce a work
on other CPUs with an empty stock.

For the current CPU we can simply call drain_local_stock rather than
deferring it to the work queue.

[kamezawa.hiroyu@jp.fujitsu.com: use drain_local_stock for current CPU optimization]
Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 82f9d486
......@@ -2180,11 +2180,8 @@ static void drain_all_stock_async(struct mem_cgroup *root_mem)
struct memcg_stock_pcp *stock = &per_cpu(memcg_stock, cpu);
struct mem_cgroup *mem;
if (cpu == curcpu)
continue;
mem = stock->cached;
if (!mem)
if (!mem || !stock->nr_pages)
continue;
if (mem != root_mem) {
if (!root_mem->use_hierarchy)
......@@ -2193,8 +2190,12 @@ static void drain_all_stock_async(struct mem_cgroup *root_mem)
if (!css_is_ancestor(&mem->css, &root_mem->css))
continue;
}
if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags))
schedule_work_on(cpu, &stock->work);
if (!test_and_set_bit(FLUSHING_CACHED_CHARGE, &stock->flags)) {
if (cpu == curcpu)
drain_local_stock(&stock->work);
else
schedule_work_on(cpu, &stock->work);
}
}
put_online_cpus();
mutex_unlock(&percpu_charge_mutex);
......
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