From mboxrd@z Thu Jan 1 00:00:00 1970 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH RFC] memcg: MEMCG_NR_FILE_MAPPED should update _STAT_CACHE as well Date: Mon, 23 Apr 2012 17:35:12 +0900 Message-ID: <4F951440.7040704@jp.fujitsu.com> References: <20120302162753.GA11748@oksana.dev.rtsoft.ru> <20120305091934.588c160b.kamezawa.hiroyu@jp.fujitsu.com> <20120423082835.GA32359@lizard> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120423082835.GA32359@lizard> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Anton Vorontsov Cc: cgroups@vger.kernel.org, Johannes Weiner , Michal Hocko , Balbir Singh , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , KOSAKI Motohiro , John Stultz , linaro-kernel@lists.linaro.org, patches@linaro.org (2012/04/23 17:28), Anton Vorontsov wrote: > ...otherwise the we're getting the wrong numbers in usage_in_bytes. > > On Mon, Mar 05, 2012 at 09:19:34AM +0900, KAMEZAWA Hiroyuki wrote: > [...] >>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >>> index 228d646..c8abdc5 100644 >>> --- a/mm/memcontrol.c >>> +++ b/mm/memcontrol.c >>> @@ -3812,6 +3812,9 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *memcg, bool swap) >>> >>> val = mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_CACHE); >>> val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_RSS); >>> + val += mem_cgroup_recursive_stat(memcg, MEM_CGROUP_STAT_FILE_MAPPED); >>> >>> 1. Is there any particular reason we don't currently account file mapped >>> memory in usage_in_bytes? >>> >>> To me, MEM_CGROUP_STAT_FILE_MAPPED hunk seems logical even if we >>> don't use it for lowmemory notifications. >>> >>> Plus, it seems that FILE_MAPPED _is_ accounted for the non-root >>> cgroups, so I guess it's clearly a bug for the root memcg? >> >> CACHE includes all file caches. Why do you think FILE_MAPPED is not included in CACHE ? > > There were tons of changes in the memcg lately, but I believe the issue > is still there. > > For example, looking into this code flow: > > -> page_add_file_rmap() (mm/rmap.c) > -> mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED) (include/linux/memcontrol.h) > -> void mem_cgroup_update_page_stat(page, MEMCG_NR_FILE_MAPPED, 1) (mm/memcontrol.c) > > And then: > > void mem_cgroup_update_page_stat(struct page *page, > enum mem_cgroup_page_stat_item idx, int val) > { > ... > switch (idx) { > case MEMCG_NR_FILE_MAPPED: > idx = MEM_CGROUP_STAT_FILE_MAPPED; > break; > default: > BUG(); > } > > this_cpu_add(memcg->stat->count[idx], val); > ... > } > > So, clearly, this function only bothers updating _FILE_MAPPED only, > leaving _CACHE alone. > > If you're saying that _CACHE meant to include _FILE_MAPPED, then > I guess the patch down below would be a proper fix then... Otherwise > we need to be consistent on stats reporting, and either fall-back > to my original fix (in mem_cgroup_usage()), or think about doing it > some other way... > NACK. CACHE is updated at charge()/uncharge()...inserting/removing page cache to radix-tree. Thanks, -Kame > Signed-off-by: Anton Vorontsov > --- > > The patch is against current -next. > > Thanks, > > mm/memcontrol.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 884e936..760ecf5 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1958,6 +1958,8 @@ void mem_cgroup_update_page_stat(struct page *page, > > switch (idx) { > case MEMCG_NR_FILE_MAPPED: > + idx = MEM_CGROUP_STAT_CACHE; > + this_cpu_add(memcg->stat->count[idx], val); > idx = MEM_CGROUP_STAT_FILE_MAPPED; > break; > default: -- 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