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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 A21E2C17441 for ; Wed, 13 Nov 2019 02:41:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7213721A49 for ; Wed, 13 Nov 2019 02:41:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7213721A49 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0702C6B0007; Tue, 12 Nov 2019 21:41:05 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 020F06B0008; Tue, 12 Nov 2019 21:41:04 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E77946B000A; Tue, 12 Nov 2019 21:41:04 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0007.hostedemail.com [216.40.44.7]) by kanga.kvack.org (Postfix) with ESMTP id D1B626B0007 for ; Tue, 12 Nov 2019 21:41:04 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 7C7AD2470 for ; Wed, 13 Nov 2019 02:41:04 +0000 (UTC) X-FDA: 76149702048.27.books77_7dae136d1a207 X-HE-Tag: books77_7dae136d1a207 X-Filterd-Recvd-Size: 2839 Received: from out30-56.freemail.mail.aliyun.com (out30-56.freemail.mail.aliyun.com [115.124.30.56]) by imf21.hostedemail.com (Postfix) with ESMTP for ; Wed, 13 Nov 2019 02:41:03 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R981e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04446;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=16;SR=0;TI=SMTPD_---0ThwxWMo_1573612858; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0ThwxWMo_1573612858) by smtp.aliyun-inc.com(127.0.0.1); Wed, 13 Nov 2019 10:40:59 +0800 Subject: Re: [PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance regression To: Matthew Wilcox Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mgorman@techsingularity.net, tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru, daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com, Johannes Weiner , Roman Gushchin , Shakeel Butt , Chris Down , Thomas Gleixner References: <1573567588-47048-1-git-send-email-alex.shi@linux.alibaba.com> <1573567588-47048-7-git-send-email-alex.shi@linux.alibaba.com> <20191112143844.GB7934@bombadil.infradead.org> From: Alex Shi Message-ID: Date: Wed, 13 Nov 2019 10:40:58 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 MIME-Version: 1.0 In-Reply-To: <20191112143844.GB7934@bombadil.infradead.org> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: quoted-printable 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: =D4=DA 2019/11/12 =CF=C2=CE=E710:38, Matthew Wilcox =D0=B4=B5=C0: > On Tue, Nov 12, 2019 at 10:06:26PM +0800, Alex Shi wrote: >> Intel 0day report there are performance regression on this patchset. >> The detailed info points to rcu_read_lock + PROVE_LOCKING which causes >> queued_spin_lock_slowpath waiting too long time to get lock. >> Remove rcu_read_lock is safe here since we had a spinlock hold. > Argh. You have not sent these patches in a properly reviewable form! > I wasted all that time reviewing the earlier patch in this series only = to > find out that you changed it here. FIX THE PATCH, don't send a fix-pat= ch > on top of it! >=20 Hi Matthew, Very sorry for your time! The main reasons I use a separate patch since a= , Intel 0day asking me to credit their are founding, and I don't know how= to give a clearly/elegant explanation for a non-exist regression in a fi= xed patch. b, this regression is kindly pretty tricky. Maybe it's better= saying thanks in version change log of cover-letter? Anyway, Thanks a lot for your review! Alex