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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 8932DC43381 for ; Wed, 3 Mar 2021 18:09:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5CF6F64EC3 for ; Wed, 3 Mar 2021 18:09:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1385543AbhCCRU1 (ORCPT ); Wed, 3 Mar 2021 12:20:27 -0500 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:34466 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233874AbhCCNmt (ORCPT ); Wed, 3 Mar 2021 08:42:49 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=xlpang@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0UQGHx3l_1614778477; Received: from xunleideMacBook-Pro.local(mailfrom:xlpang@linux.alibaba.com fp:SMTPD_---0UQGHx3l_1614778477) by smtp.aliyun-inc.com(127.0.0.1); Wed, 03 Mar 2021 21:34:38 +0800 Reply-To: xlpang@linux.alibaba.com Subject: Re: [PATCH v2 0/3] mm/slub: Fix count_partial() problem To: Shu Ming , xlpang@linux.alibaba.com Cc: Pekka Enberg , Vlastimil Babka , Christoph Lameter , Wen Yang , Roman Gushchin , Konstantin Khlebnikov , David Rientjes , LKML , "linux-mm@kvack.org" References: <1597061872-58724-1-git-send-email-xlpang@linux.alibaba.com> From: Xunlei Pang Message-ID: Date: Wed, 3 Mar 2021 21:34:37 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/1/21 6:31 PM, Shu Ming wrote: > Any progress on this? The problem addressed by this patch has also > made jitters to our online apps which are quite annoying. > Thanks for the attention. There's some further improvements on v2, I'm gonna send v3 out later. > On Mon, Aug 24, 2020 at 6:05 PM xunlei wrote: >> >> On 2020/8/20 下午10:02, Pekka Enberg wrote: >>> On Mon, Aug 10, 2020 at 3:18 PM Xunlei Pang wrote: >>>> >>>> v1->v2: >>>> - Improved changelog and variable naming for PATCH 1~2. >>>> - PATCH3 adds per-cpu counter to avoid performance regression >>>> in concurrent __slab_free(). >>>> >>>> [Testing] >>>> On my 32-cpu 2-socket physical machine: >>>> Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz >>>> perf stat --null --repeat 10 -- hackbench 20 thread 20000 >>>> >>>> == original, no patched >>>> 19.211637055 seconds time elapsed ( +- 0.57% ) >>>> >>>> == patched with patch1~2 >>>> Performance counter stats for 'hackbench 20 thread 20000' (10 runs): >>>> >>>> 21.731833146 seconds time elapsed ( +- 0.17% ) >>>> >>>> == patched with patch1~3 >>>> Performance counter stats for 'hackbench 20 thread 20000' (10 runs): >>>> >>>> 19.112106847 seconds time elapsed ( +- 0.64% ) >>>> >>>> >>>> Xunlei Pang (3): >>>> mm/slub: Introduce two counters for partial objects >>>> mm/slub: Get rid of count_partial() >>>> mm/slub: Use percpu partial free counter >>>> >>>> mm/slab.h | 2 + >>>> mm/slub.c | 124 +++++++++++++++++++++++++++++++++++++++++++------------------- >>>> 2 files changed, 89 insertions(+), 37 deletions(-) >>> >>> We probably need to wrap the counters under CONFIG_SLUB_DEBUG because >>> AFAICT all the code that uses them is also wrapped under it. >> >> /sys/kernel/slab/***/partial sysfs also uses it, I can wrap it with >> CONFIG_SLUB_DEBUG or CONFIG_SYSFS for backward compatibility. >> >>> >>> An alternative approach for this patch would be to somehow make the >>> lock in count_partial() more granular, but I don't know how feasible >>> that actually is. >>> >>> Anyway, I am OK with this approach: >>> >>> Reviewed-by: Pekka Enberg >> >> Thanks! >> >>> >>> You still need to convince Christoph, though, because he had >>> objections over this approach. >> >> Christoph, what do you think, or any better suggestion to address this >> *in production* issue? >> >>> >>> - Pekka >>>