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=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 41A90C388F7 for ; Fri, 13 Nov 2020 07:34:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4F1920936 for ; Fri, 13 Nov 2020 07:34:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726414AbgKMHeo (ORCPT ); Fri, 13 Nov 2020 02:34:44 -0500 Received: from mga18.intel.com ([134.134.136.126]:5675 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726112AbgKMHeo (ORCPT ); Fri, 13 Nov 2020 02:34:44 -0500 IronPort-SDR: jfvWP1gre8yybNfusGXdRzLexlhNsyg8fsDdoBc/1KzUz6GzivQbKbi5U3FdTC68R5D2kgi/xf Fjl5i893/ZuA== X-IronPort-AV: E=McAfee;i="6000,8403,9803"; a="158216693" X-IronPort-AV: E=Sophos;i="5.77,474,1596524400"; d="scan'208";a="158216693" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Nov 2020 23:34:41 -0800 IronPort-SDR: sQokg6Hx0MJz/Qpl4kQ0X6r+3xMgUTOGei0UkMY5FdtEADGTOybbLM7NZWtUmG1yH0qj7lA0V4 +tuV/X/S5ggA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,474,1596524400"; d="scan'208";a="532475822" Received: from shbuild999.sh.intel.com (HELO localhost) ([10.239.147.98]) by fmsmga005.fm.intel.com with ESMTP; 12 Nov 2020 23:34:37 -0800 Date: Fri, 13 Nov 2020 15:34:36 +0800 From: Feng Tang To: Michal Hocko Cc: Xing Zhengjun , Waiman Long , Linus Torvalds , Andrew Morton , Shakeel Butt , Chris Down , Johannes Weiner , Roman Gushchin , Tejun Heo , Vladimir Davydov , Yafang Shao , LKML , lkp@lists.01.org, lkp@intel.com, zhengjun.xing@intel.com, ying.huang@intel.com Subject: Re: [LKP] Re: [mm/memcg] bd0b230fe1: will-it-scale.per_process_ops -22.7% regression Message-ID: <20201113073436.GA113119@shbuild999.sh.intel.com> References: <20201102091543.GM31092@shao2-debian> <20201102092754.GD22613@dhcp22.suse.cz> <82d73ebb-a31e-4766-35b8-82afa85aa047@intel.com> <20201102100247.GF22613@dhcp22.suse.cz> <20201104081546.GB10052@dhcp22.suse.cz> <20201112122844.GA11000@shbuild999.sh.intel.com> <20201112141654.GC12240@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201112141654.GC12240@dhcp22.suse.cz> User-Agent: Mutt/1.5.24 (2015-08-30) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 12, 2020 at 03:16:54PM +0100, Michal Hocko wrote: > On Thu 12-11-20 20:28:44, Feng Tang wrote: > > Hi Michal, > > > > On Wed, Nov 04, 2020 at 09:15:46AM +0100, Michal Hocko wrote: > > > > > > Hi Michal, > > > > > > > > > > > > We used the default configure of cgroups, not sure what configuration you > > > > > > want, > > > > > > could you give me more details? and here is the cgroup info of will-it-scale > > > > > > process: > > > > > > > > > > > > $ cat /proc/3042/cgroup > > > > > > 12:hugetlb:/ > > > > > > 11:memory:/system.slice/lkp-bootstrap.service > > > > > > > > > > OK, this means that memory controler is enabled and in use. Btw. do you > > > > > get the original performance if you add one phony page_counter after the > > > > > union? > > > > > > > > > I add one phony page_counter after the union and re-test, the regression > > > > reduced to -1.2%. It looks like the regression caused by the data structure > > > > layout change. > > > > > > Thanks for double checking. Could you try to cache align the > > > page_counter struct? If that helps then we should figure which counters > > > acks against each other by adding the alignement between the respective > > > counters. > > > > We tried below patch to make the 'page_counter' aligned. > > > > diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h > > index bab7e57..9efa6f7 100644 > > --- a/include/linux/page_counter.h > > +++ b/include/linux/page_counter.h > > @@ -26,7 +26,7 @@ struct page_counter { > > /* legacy */ > > unsigned long watermark; > > unsigned long failcnt; > > -}; > > +} ____cacheline_internodealigned_in_smp; > > > > and with it, the -22.7% peformance change turns to a small -1.7%, which > > confirms the performance bump is caused by the change to data alignment. > > > > After the patch, size of 'page_counter' increases from 104 bytes to 128 > > bytes, and the size of 'mem_cgroup' increases from 2880 bytes to 3008 > > bytes(with our kernel config). Another major data structure which > > contains 'page_counter' is 'hugetlb_cgroup', whose size will change > > from 912B to 1024B. > > > > Should we make these page_counters aligned to reduce cacheline conflict? > > I would rather focus on a more effective mem_cgroup layout. It is very > likely that we are just stumbling over two counters here. > > Could you try to add cache alignment of counters after memory and see > which one makes the difference? I do not expect memsw to be the one > because that one is used together with the main counter. But who knows > maybe the way it crosses the cache line has the exact effect. Hard to > tell without other numbers. I added some alignments change around the 'memsw', but neither of them can restore the -22.7%. Following are some log showing how the alignments are: tl: memcg=0x7cd1000 memory=0x7cd10d0 memsw=0x7cd1140 kmem=0x7cd11b0 tcpmem=0x7cd1220 t2: memcg=0x7cd0000 memory=0x7cd00d0 memsw=0x7cd0140 kmem=0x7cd01c0 tcpmem=0x7cd0230 So both of the 'memsw' are aligned, but t2's 'kmem' is aligned while t1's is not. I will check more on the perf data about detailed hotspots. Thanks, Feng > Btw. it would be great to see what the effect is on cgroup v2 as well. > > Thanks for pursuing this! > -- > Michal Hocko > SUSE Labs