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 9DEDBC433E1 for ; Tue, 21 Jul 2020 03:07:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6C89320734 for ; Tue, 21 Jul 2020 03:07:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C89320734 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CF2FB6B0010; Mon, 20 Jul 2020 23:07:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CA4408D0001; Mon, 20 Jul 2020 23:07:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BB9D56B0025; Mon, 20 Jul 2020 23:07:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0064.hostedemail.com [216.40.44.64]) by kanga.kvack.org (Postfix) with ESMTP id A81DC6B0010 for ; Mon, 20 Jul 2020 23:07:56 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 29190801A3CB for ; Tue, 21 Jul 2020 03:07:56 +0000 (UTC) X-FDA: 77060598552.10.noise45_481021626f2a Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin10.hostedemail.com (Postfix) with ESMTP id F36C58072B86 for ; Tue, 21 Jul 2020 03:07:55 +0000 (UTC) X-HE-Tag: noise45_481021626f2a X-Filterd-Recvd-Size: 1839 Received: from out30-42.freemail.mail.aliyun.com (out30-42.freemail.mail.aliyun.com [115.124.30.42]) by imf14.hostedemail.com (Postfix) with ESMTP for ; Tue, 21 Jul 2020 03:07:54 +0000 (UTC) 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 X-Rspamd-Queue-Id: F36C58072B86 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.018067, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: =D4=DA 2020/7/21 =C9=CF=CE=E77:14, Andrew Morton =D0=B4=B5=C0: >> --- 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; >> =20 >> + if (unlikely(!delta)) >> + return; >> + > Do we know that delta=3D=3D0 is frequent enough to make the change a ne= t > benefit? Uh,I check again. it seems no much place delta=3D=3D0, forget this patch. Thanks Alex