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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 28C91C56201 for ; Thu, 26 Nov 2020 03:13:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C9259216C4 for ; Thu, 26 Nov 2020 03:12:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733249AbgKZDMn (ORCPT ); Wed, 25 Nov 2020 22:12:43 -0500 Received: from out4436.biz.mail.alibaba.com ([47.88.44.36]:8944 "EHLO out4436.biz.mail.alibaba.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732389AbgKZDMn (ORCPT ); Wed, 25 Nov 2020 22:12:43 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0UGYkbqq_1606360350; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0UGYkbqq_1606360350) by smtp.aliyun-inc.com(127.0.0.1); Thu, 26 Nov 2020 11:12:31 +0800 Subject: Re: [PATCH next] mm/swap.c: reduce lock contention in lru_cache_add To: Vlastimil Babka Cc: Konstantin Khlebnikov , Andrew Morton , Hugh Dickins , Yu Zhao , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1605860847-47445-1-git-send-email-alex.shi@linux.alibaba.com> From: Alex Shi Message-ID: Date: Thu, 26 Nov 2020 11:12:30 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 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 在 2020/11/25 下午11:38, Vlastimil Babka 写道: > On 11/20/20 9:27 AM, Alex Shi wrote: >> The current relock logical will change lru_lock when found a new >> lruvec, so if 2 memcgs are reading file or alloc page at same time, >> they could hold the lru_lock alternately, and wait for each other for >> fairness attribute of ticket spin lock. >> >> This patch will sort that all lru_locks and only hold them once in >> above scenario. That could reduce fairness waiting for lock reget. >> Than, vm-scalability/case-lru-file-readtwice could get ~5% performance >> gain on my 2P*20core*HT machine. > > Hm, once you sort the pages like this, it's a shame not to splice them instead of more list_del() + list_add() iterations. update_lru_size() could be also called once? Yes, looks it's a good idea to use splice instead of list_del/add, but pages may on different lru list in a same lruvec, and also may come from different zones. That could involve 5 cycles for different lists, and more for zones... I give up the try.