From 0deea1cf551e3f63a57960cb7b61e1ef4fb2c8ca Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Tue, 26 Jul 2011 16:08:27 -0700 Subject: [PATCH] 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: Michal Hocko Cc: KAMEZAWA Hiroyuki Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 04e505bfd7dd3..2f5534e1968ca 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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); -- 2.39.5