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 D27C8C43331 for ; Wed, 13 Nov 2019 02:41:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2F63206BA for ; Wed, 13 Nov 2019 02:41:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727698AbfKMClD (ORCPT ); Tue, 12 Nov 2019 21:41:03 -0500 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:57903 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727474AbfKMClD (ORCPT ); Tue, 12 Nov 2019 21:41:03 -0500 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: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2019/11/12 ÏÂÎç10:38, Matthew Wilcox дµÀ: > 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-patch > on top of it! > 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 fixed 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