From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3D39C3F2D7 for ; Fri, 6 Mar 2020 04:54:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 75D5020866 for ; Fri, 6 Mar 2020 04:54:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="PThzNVAb" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 75D5020866 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1E8B06B0005; Thu, 5 Mar 2020 23:54:52 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 19A046B0006; Thu, 5 Mar 2020 23:54:52 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0D7126B0007; Thu, 5 Mar 2020 23:54:52 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0033.hostedemail.com [216.40.44.33]) by kanga.kvack.org (Postfix) with ESMTP id E995F6B0005 for ; Thu, 5 Mar 2020 23:54:51 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id BC8002DFA for ; Fri, 6 Mar 2020 04:54:51 +0000 (UTC) X-FDA: 76563722382.10.ants10_478867c77be52 X-HE-Tag: ants10_478867c77be52 X-Filterd-Recvd-Size: 6470 Received: from mail-oi1-f193.google.com (mail-oi1-f193.google.com [209.85.167.193]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Fri, 6 Mar 2020 04:54:51 +0000 (UTC) Received: by mail-oi1-f193.google.com with SMTP id j80so1326107oih.7 for ; Thu, 05 Mar 2020 20:54:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=MpUAWMUZ0nsUfjEg79z9N04zH9L3RObZfUg0695PRvk=; b=PThzNVAb6Nb1Dfs+tTbDHirwjN0U1rIcenmtDKH0p7vqy2XWlgokbVbIYqRGQWFwQX wwtqxkSLN5LqkNYuJQRcOhRxIMHGiB52X8885xTN1Myga1uwq+A3689vLEHE1jTa9yvt 7p3DuEO/yvgD5KYCwWVI26lI8BEi7fd4TcJ6H66rZmbwyUyFA4HwuceyNgXIqEhNftSH j7M3EqnuUOqbrpoAG/FjA5ik4f0oHTQaSJU1TUGatZqv6BXBcRSbZTf7geDYUr6yKBLM 7PQ1WOzT/U618Jey0i7perutOpaK+eqOQK48LGrLLzqKLr264H8nNi2YvS2phDsTB20r 4yQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=MpUAWMUZ0nsUfjEg79z9N04zH9L3RObZfUg0695PRvk=; b=RkzfUM+oSc233V/ESiLGvehf7KB6cC2PVV7IENfKmlg3vM9jCifWOqz2yMAa40eSqE KbkHQdCpEY8K2oEfpc/01HwzUWdcSdjkKITiLSRYLMLkXkJLMYK0uyWC2hZpNc3PDZM/ EuN4ZPRiUYiUK0mCeRLncNAYZXlOP/XemMaQ5J9sWZPXhl/7noTUpCgo9f4GHiqwV5HE RSNswwQBy8MeNDtmxoK3hp6KarheRA+a2cdRdcBqhNbIHt2fSSjGYkJfoZWwmYWri5Ia oqLux1JD68O4e/sKSKvWcmsDQj/vaVSqfFL94IEQyDTp2kN6wpRsQx17pBJ31mHfRQ8U xG5A== X-Gm-Message-State: ANhLgQ1rIFFuFcjLixPo6rm8dR8pJRruqjfSEoxgPvNleo6jfyPDZ6p1 sGBQlVoAt7cHAKb7kQLKienAeFu0w628WpHsro/Y+A== X-Google-Smtp-Source: ADFU+vtNxEjhXH7+aG4thzPjJN/ZYpMvSrgzN5M2VSoSCqw6I671cwU1GUgJpvbLweYoi5YLQXLi2l+PSLl10Zyutrg= X-Received: by 2002:aca:52c7:: with SMTP id g190mr1323278oib.144.1583470490279; Thu, 05 Mar 2020 20:54:50 -0800 (PST) MIME-Version: 1.0 References: <20200304022058.248270-1-shakeelb@google.com> <20200305204109.be23f5053e2368d3b8ccaa06@linux-foundation.org> In-Reply-To: <20200305204109.be23f5053e2368d3b8ccaa06@linux-foundation.org> From: Shakeel Butt Date: Thu, 5 Mar 2020 20:54:39 -0800 Message-ID: Subject: Re: [PATCH] memcg: optimize memory.numa_stat like memory.stat To: Andrew Morton Cc: Johannes Weiner , Roman Gushchin , Michal Hocko , Linux MM , Cgroups , LKML Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 5, 2020 at 8:41 PM Andrew Morton wrote: > > On Tue, 3 Mar 2020 18:20:58 -0800 Shakeel Butt wrote: > > > Currently reading memory.numa_stat traverses the underlying memcg tree > > multiple times to accumulate the stats to present the hierarchical view > > of the memcg tree. However the kernel already maintains the hierarchical > > view of the stats and use it in memory.stat. Just use the same mechanism > > in memory.numa_stat as well. > > > > I ran a simple benchmark which reads root_mem_cgroup's memory.numa_stat > > file in the presense of 10000 memcgs. The results are: > > > > Without the patch: > > $ time cat /dev/cgroup/memory/memory.numa_stat > /dev/null > > > > real 0m0.700s > > user 0m0.001s > > sys 0m0.697s > > > > With the patch: > > $ time cat /dev/cgroup/memory/memory.numa_stat > /dev/null > > > > real 0m0.001s > > user 0m0.001s > > sys 0m0.000s > > > > Can't you do better than that ;) > > > > > + page_state = tree ? lruvec_page_state : lruvec_page_state_local; > > ... > > > > + page_state = tree ? memcg_page_state : memcg_page_state_local; > > > > All four of these functions are inlined. Taking their address in this > fashion will force the compiler to generate out-of-line copies. > > If we do it the uglier-and-maybe-a-bit-slower way: > > --- a/mm/memcontrol.c~memcg-optimize-memorynuma_stat-like-memorystat-fix > +++ a/mm/memcontrol.c > @@ -3658,17 +3658,16 @@ static unsigned long mem_cgroup_node_nr_ > struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid)); > unsigned long nr = 0; > enum lru_list lru; > - unsigned long (*page_state)(struct lruvec *lruvec, > - enum node_stat_item idx); > > VM_BUG_ON((unsigned)nid >= nr_node_ids); > > - page_state = tree ? lruvec_page_state : lruvec_page_state_local; > - > for_each_lru(lru) { > if (!(BIT(lru) & lru_mask)) > continue; > - nr += page_state(lruvec, NR_LRU_BASE + lru); > + if (tree) > + nr += lruvec_page_state(lruvec, NR_LRU_BASE + lru); > + else > + nr += lruvec_page_state_local(lruvec, NR_LRU_BASE + lru); > } > return nr; > } > @@ -3679,14 +3678,14 @@ static unsigned long mem_cgroup_nr_lru_p > { > unsigned long nr = 0; > enum lru_list lru; > - unsigned long (*page_state)(struct mem_cgroup *memcg, int idx); > - > - page_state = tree ? memcg_page_state : memcg_page_state_local; > > for_each_lru(lru) { > if (!(BIT(lru) & lru_mask)) > continue; > - nr += page_state(memcg, NR_LRU_BASE + lru); > + if (tree) > + nr += memcg_page_state(memcg, NR_LRU_BASE + lru); > + else > + nr += memcg_page_state_local(memcg, NR_LRU_BASE + lru); > } > return nr; > } > > Then we get: > > text data bss dec hex filename > now: 106705 35641 1024 143370 2300a mm/memcontrol.o > shakeel: 107111 35657 1024 143792 231b0 mm/memcontrol.o > shakeel+the-above: 106805 35657 1024 143486 2307e mm/memcontrol.o > > Which do we prefer? The 100-byte patch or the 406-byte patch? I would go with the 100-byte one. The for-loop is just 5 iteration, so doing a check in each iteration should not be an issue. Shakeel