From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx134.postini.com [74.125.245.134]) by kanga.kvack.org (Postfix) with SMTP id 916546B006E for ; Sat, 5 Jan 2013 02:38:33 -0500 (EST) Received: by mail-ie0-f171.google.com with SMTP id 17so20851220iea.30 for ; Fri, 04 Jan 2013 23:38:32 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <50DCF00B.5040100@jp.fujitsu.com> References: <1356455919-14445-1-git-send-email-handai.szj@taobao.com> <1356456447-14740-1-git-send-email-handai.szj@taobao.com> <50DCF00B.5040100@jp.fujitsu.com> Date: Sat, 5 Jan 2013 15:38:32 +0800 Message-ID: Subject: Re: [PATCH V3 6/8] memcg: Don't account root_mem_cgroup page statistics From: Sha Zhengju Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Kamezawa Hiroyuki Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.cz, akpm@linux-foundation.org, gthelen@google.com, fengguang.wu@intel.com, glommer@parallels.com, Sha Zhengju On Fri, Dec 28, 2012 at 9:04 AM, Kamezawa Hiroyuki wrote: > (2012/12/26 2:27), Sha Zhengju wrote: >> From: Sha Zhengju >> >> If memcg is enabled and no non-root memcg exists, all allocated pages >> belongs to root_mem_cgroup and go through root memcg statistics routines >> which brings some overheads. So for the sake of performance, we can give >> up accounting stats of root memcg for MEM_CGROUP_STAT_FILE_MAPPED/FILE_DIRTY >> /WRITEBACK and instead we pay special attention while showing root >> memcg numbers in memcg_stat_show(): as we don't account root memcg stats >> anymore, the root_mem_cgroup->stat numbers are actually 0. But because of >> hierachy, figures of root_mem_cgroup may just represent numbers of pages >> used by its own tasks(not belonging to any other child cgroup). So here we >> fake these root numbers by using stats of global state and all other memcg. >> That is for root memcg: >> nr(MEM_CGROUP_STAT_FILE_MAPPED) = global_page_state(NR_FILE_MAPPED) - >> sum_of_all_memcg(MEM_CGROUP_STAT_FILE_MAPPED); >> Dirty/Writeback pages accounting are in the similar way. >> >> Signed-off-by: Sha Zhengju > > isn't it better to use mem_cgroup_is_root() call rather than > direct comparison (memcg == root_mem_cgroup) ? > Okay, it's better to use the wrapper. > Anyway, Ack to this approach. > Thanks for reviewing! Regards, Sha -- 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/ . Don't email: email@kvack.org