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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 1E755C3F2CD for ; Fri, 6 Mar 2020 04:41:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BB87320848 for ; Fri, 6 Mar 2020 04:41:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="mGdiXoYe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BB87320848 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 302696B0005; Thu, 5 Mar 2020 23:41:12 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 28C5E6B0006; Thu, 5 Mar 2020 23:41:12 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 17B526B0007; Thu, 5 Mar 2020 23:41:12 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0115.hostedemail.com [216.40.44.115]) by kanga.kvack.org (Postfix) with ESMTP id EF0C36B0005 for ; Thu, 5 Mar 2020 23:41:11 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id ACEE64DD0 for ; Fri, 6 Mar 2020 04:41:11 +0000 (UTC) X-FDA: 76563687942.24.tin64_61b058868d550 X-HE-Tag: tin64_61b058868d550 X-Filterd-Recvd-Size: 4537 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Fri, 6 Mar 2020 04:41:11 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 05C832072D; Fri, 6 Mar 2020 04:41:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583469670; bh=jMaNzWwGNyJXrXRBCiJpddGoeLBF0dNI2ZOpUjqJRJQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=mGdiXoYeYvFstIQEK7caAUrHjH8h4/xKtNznaLuGjgXgOFKJjYQw11NyqgTvnY4/M sU4aRm7gnUt4at7lCieJSD8xlulHfvn+rD51LaJwEQWd5XjtV4rrtX+TQA7R24EV2o Gz7apFZYMLJ5s7t0ZDiIIkveSU4NKvblbLuQXVFM= Date: Thu, 5 Mar 2020 20:41:09 -0800 From: Andrew Morton To: Shakeel Butt Cc: Johannes Weiner , Roman Gushchin , Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] memcg: optimize memory.numa_stat like memory.stat Message-Id: <20200305204109.be23f5053e2368d3b8ccaa06@linux-foundation.org> In-Reply-To: <20200304022058.248270-1-shakeelb@google.com> References: <20200304022058.248270-1-shakeelb@google.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 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?