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=-5.2 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 5A060C56202 for ; Thu, 26 Nov 2020 06:39:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 075C120B80 for ; Thu, 26 Nov 2020 06:39:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388082AbgKZGjH (ORCPT ); Thu, 26 Nov 2020 01:39:07 -0500 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]:41037 "EHLO out30-133.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731252AbgKZGjH (ORCPT ); Thu, 26 Nov 2020 01:39:07 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R761e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0UGZY9rf_1606372743; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0UGZY9rf_1606372743) by smtp.aliyun-inc.com(127.0.0.1); Thu, 26 Nov 2020 14:39:03 +0800 Subject: Re: [PATCH next] mm/swap.c: reduce lock contention in lru_cache_add To: Yu Zhao Cc: Konstantin Khlebnikov , Andrew Morton , Hugh Dickins , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1605860847-47445-1-git-send-email-alex.shi@linux.alibaba.com> <20201126045234.GA1014081@google.com> From: Alex Shi Message-ID: Date: Thu, 26 Nov 2020 14:39:03 +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: <20201126045234.GA1014081@google.com> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ÔÚ 2020/11/26 ÏÂÎç12:52, Yu Zhao дµÀ: >> */ >> void __pagevec_lru_add(struct pagevec *pvec) >> { >> - int i; >> - struct lruvec *lruvec = NULL; >> + int i, nr_lruvec; >> unsigned long flags = 0; >> + struct page *page; >> + struct lruvecs lruvecs; >> >> - for (i = 0; i < pagevec_count(pvec); i++) { >> - struct page *page = pvec->pages[i]; >> + nr_lruvec = sort_page_lruvec(&lruvecs, pvec); > Simply looping pvec multiple times (15 at most) for different lruvecs > would be better because 1) it requires no extra data structures and > therefore has better cache locality (theoretically faster) 2) it only > loops once when !CONFIG_MEMCG and !CONFIG_NUMA and therefore has no > impact on Android and Chrome OS. > With multiple memcgs, it do help a lot, I had gotten 30% grain on readtwice case. but yes, w/o MEMCG and NUMA, it's good to keep old behavior. So would you like has a proposal for this? Thanks Alex