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=-5.5 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 C865FC433E0 for ; Tue, 21 Jul 2020 03:07:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D12820734 for ; Tue, 21 Jul 2020 03:07:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728296AbgGUDHy (ORCPT ); Mon, 20 Jul 2020 23:07:54 -0400 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]:33774 "EHLO out30-133.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726264AbgGUDHx (ORCPT ); Mon, 20 Jul 2020 23:07:53 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R481e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=3;SR=0;TI=SMTPD_---0U3Ml0pk_1595300870; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U3Ml0pk_1595300870) by smtp.aliyun-inc.com(127.0.0.1); Tue, 21 Jul 2020 11:07:50 +0800 Subject: Re: [PATCH] mm/vmstat: don't do count if no needs To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20200720052348.428564-1-alex.shi@linux.alibaba.com> <1ef9baa0-9788-5917-2590-a8c3fc593b81@linux.alibaba.com> <20200720161404.bd0c24560114bf48d6acbaff@linux-foundation.org> From: Alex Shi Message-ID: <757accf7-81bf-442c-f144-4cad52fea4a5@linux.alibaba.com> Date: Tue, 21 Jul 2020 11:07:48 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200720161404.bd0c24560114bf48d6acbaff@linux-foundation.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 2020/7/21 ÉÏÎç7:14, Andrew Morton дµÀ: >> --- a/mm/vmstat.c >> +++ b/mm/vmstat.c >> @@ -321,6 +321,9 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item, >> long x; >> long t; >> >> + if (unlikely(!delta)) >> + return; >> + > Do we know that delta==0 is frequent enough to make the change a net > benefit? Uh,I check again. it seems no much place delta==0, forget this patch. Thanks Alex