From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx129.postini.com [74.125.245.129]) by kanga.kvack.org (Postfix) with SMTP id D70946B004D for ; Sat, 21 Jan 2012 09:49:24 -0500 (EST) Received: by wicr5 with SMTP id r5so1462935wic.14 for ; Sat, 21 Jan 2012 06:49:23 -0800 (PST) MIME-Version: 1.0 Date: Sat, 21 Jan 2012 22:49:23 +0800 Message-ID: Subject: [PATCH] mm: memcg: fix over reclaiming mem cgroup From: Hillf Danton Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Michal Hocko , KAMEZAWA Hiroyuki , Ying Han , Hugh Dickins , Andrew Morton , LKML , Hillf Danton In soft limit reclaim, overreclaim occurs when pages are reclaimed from mem group that is under its soft limit, or when more pages are reclaimd than the exceeding amount, then performance of reclaimee goes down accordingly. A helper function is added to compute the number of pages that exceed the soft limit of given mem cgroup, then the excess pages are used when every reclaimee is reclaimed to avoid overreclaim. Signed-off-by: Hillf Danton --- --- a/mm/memcontrol.c Tue Jan 17 20:41:36 2012 +++ b/mm/memcontrol.c Sat Jan 21 21:18:46 2012 @@ -1662,6 +1662,21 @@ static int mem_cgroup_soft_reclaim(struc return total; } +unsigned long mem_cgroup_excess_pages(struct mem_cgroup *memcg) +{ + unsigned long pages; + + if (mem_cgroup_disabled()) + return 0; + if (!memcg) + return 0; + if (mem_cgroup_is_root(memcg)) + return 0; + + pages = res_counter_soft_limit_excess(&memcg->res) >> PAGE_SHIFT; + return pages; +} + /* * Check OOM-Killer is already running under our hierarchy. * If someone is running, return false. --- a/mm/vmscan.c Sat Jan 14 14:02:20 2012 +++ b/mm/vmscan.c Sat Jan 21 21:30:06 2012 @@ -2150,8 +2150,34 @@ static void shrink_zone(int priority, st .mem_cgroup = memcg, .zone = zone, }; + unsigned long old; + bool clobbered = false; + + if (memcg != NULL) { + unsigned long excess; + + excess = mem_cgroup_excess_pages(memcg); + /* + * No bother reclaiming pages from mem cgroup that + * is under soft limit + */ + if (!excess) + goto next; + /* + * And reclaim no more pages than excess + */ + if (excess < sc->nr_to_reclaim) { + old = sc->nr_to_reclaim; + sc->nr_to_reclaim = excess; + clobbered = true; + } + } shrink_mem_cgroup_zone(priority, &mz, sc); + + if (clobbered) + sc->nr_to_reclaim = old; +next: /* * Limit reclaim has historically picked one memcg and * scanned it with decreasing priority levels until --- a/include/linux/memcontrol.h Thu Jan 19 22:03:14 2012 +++ b/include/linux/memcontrol.h Sat Jan 21 21:35:50 2012 @@ -161,6 +161,7 @@ unsigned long mem_cgroup_soft_limit_recl gfp_t gfp_mask, unsigned long *total_scanned); u64 mem_cgroup_get_limit(struct mem_cgroup *memcg); +unsigned long mem_cgroup_excess_pages(struct mem_cgroup *memcg); void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx); #ifdef CONFIG_TRANSPARENT_HUGEPAGE @@ -376,6 +377,11 @@ unsigned long mem_cgroup_soft_limit_recl static inline u64 mem_cgroup_get_limit(struct mem_cgroup *memcg) +{ + return 0; +} + +static inline unsigned long mem_cgroup_excess_pages(struct mem_cgroup *memcg) { return 0; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org