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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 B6560C433E0 for ; Tue, 16 Mar 2021 13:32:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8104165053 for ; Tue, 16 Mar 2021 13:32:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235082AbhCPNcW (ORCPT ); Tue, 16 Mar 2021 09:32:22 -0400 Received: from mx2.suse.de ([195.135.220.15]:54928 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235081AbhCPNb5 (ORCPT ); Tue, 16 Mar 2021 09:31:57 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1615901516; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=8svTfIyJTaVROFKYlQfsMsGIUrlyGzzyIqCVIWqxArY=; b=ENhZ/Ea0rqxCFArUQgZIJwni2mFnvIFyqXxY2vAiR07jDO6jM2vVlJqMoem6bhiplcbIcd tHwk+LNFOwjW1CsUGqrNJJF0cZE0WJWeQPKpIRFI0ybDj1bCHawyrRaWRMHPqzgD6ULoEX i1UgogLMyr4N6Ko2sJWcuhq788XIIsc= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 7A892AD74; Tue, 16 Mar 2021 13:31:56 +0000 (UTC) Date: Tue, 16 Mar 2021 14:31:53 +0100 From: Michal Hocko To: Linus Torvalds Cc: kernel test robot , Muchun Song , Shakeel Butt , Johannes Weiner , Vladimir Davydov , Roman Gushchin , Stephen Rothwell , Chris Down , Yafang Shao , Wei Yang , Andrew Morton , LKML , lkp@lists.01.org, kernel test robot , "Huang, Ying" , Feng Tang , zhengjun.xing@intel.com Subject: Re: [mm] f3344adf38: fxmark.hdd_btrfs_DWAL_63_bufferedio.works/sec -52.4% regression Message-ID: References: <20210315062808.GA837@xsang-OptiPlex-9020> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 15-03-21 13:42:50, Linus Torvalds wrote: > If somebody can actually figure out what happened there, that would be > good, but for now it goes into my "archived as a random outlier" > folder. This is not something new. We have seen reports like that in the past already. In many cases there was no apparent reason except for potential code alignment: e.g. http://lkml.kernel.org/r/20200409135029.GA2072@xsang-OptiPlex-9020 There were some other memcg related which didn't really show any increase in cache misses or similar. I cannot find those in my notes right now. There were others like https://lore.kernel.org/lkml/20201102091543.GM31092@shao2-debian/ with analysis http://lkml.kernel.org/r/20201125062445.GA51005@shbuild999.sh.intel.com which actually pointed to something legit actually. For this particular report I do not see any real relation to the patch either. -- Michal Hocko SUSE Labs