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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 71DC5C433DF for ; Wed, 24 Jun 2020 19:18:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DB48320702 for ; Wed, 24 Jun 2020 19:18:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB48320702 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 836ED6B000A; Wed, 24 Jun 2020 15:18:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7E8716B000C; Wed, 24 Jun 2020 15:18:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7243B6B000D; Wed, 24 Jun 2020 15:18:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0235.hostedemail.com [216.40.44.235]) by kanga.kvack.org (Postfix) with ESMTP id 58FD36B000A for ; Wed, 24 Jun 2020 15:18:21 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 15D64181AC9CB for ; Wed, 24 Jun 2020 19:18:21 +0000 (UTC) X-FDA: 76965066402.29.value53_37095ac26e46 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin29.hostedemail.com (Postfix) with ESMTP id E3BC818086CD2 for ; Wed, 24 Jun 2020 19:18:20 +0000 (UTC) X-HE-Tag: value53_37095ac26e46 X-Filterd-Recvd-Size: 3356 Received: from out4436.biz.mail.alibaba.com (out4436.biz.mail.alibaba.com [47.88.44.36]) by imf03.hostedemail.com (Postfix) with ESMTP for ; Wed, 24 Jun 2020 19:18:19 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R621e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07425;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0U0cnbjv_1593026284; Received: from US-143344MP.local(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0U0cnbjv_1593026284) by smtp.aliyun-inc.com(127.0.0.1); Thu, 25 Jun 2020 03:18:06 +0800 Subject: Re: [PATCH] mm: filemap: clear idle flag for writes To: Andrew Morton Cc: hannes@cmpxchg.org, riel@surriel.com, shakeelb@google.com, gavin.dg@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1593020612-13051-1-git-send-email-yang.shi@linux.alibaba.com> <20200624115317.792d8fc6369d421d2898ab2f@linux-foundation.org> From: Yang Shi Message-ID: Date: Wed, 24 Jun 2020 12:18:02 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20200624115317.792d8fc6369d421d2898ab2f@linux-foundation.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Rspamd-Queue-Id: E3BC818086CD2 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 6/24/20 11:53 AM, Andrew Morton wrote: > On Thu, 25 Jun 2020 01:43:32 +0800 Yang Shi wrote: > >> Since commit bbddabe2e436aa7869b3ac5248df5c14ddde0cbf ("mm: filemap: >> only do access activations on reads"), mark_page_accessed() is called >> for reads only. But the idle flag is cleared by mark_page_accessed() so >> the idle flag won't get cleared if the page is write accessed only. >> >> Basically idle page tracking is used to estimate workingset size of >> workload, noticeable size of workingset might be missed if the idle flag >> is not maintained correctly. >> >> It seems good enough to just clear idle flag for write operations. >> >> ... >> >> --- a/mm/filemap.c >> +++ b/mm/filemap.c >> @@ -41,6 +41,7 @@ >> #include >> #include >> #include >> +#include >> #include "internal.h" >> >> #define CREATE_TRACE_POINTS >> @@ -1630,6 +1631,11 @@ struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index, >> >> if (fgp_flags & FGP_ACCESSED) >> mark_page_accessed(page); >> + else if (fgp_flags & FGP_WRITE) { >> + /* Clear idle flag for buffer write */ >> + if (page_is_idle(page)) >> + clear_page_idle(page); >> + } >> >> no_page: >> if (!page && (fgp_flags & FGP_CREAT)) { > The kerneldoc comment for pagecache_get_page() could do with some > updating - it fails to mention FGP_WRITE, FGP_NOFS and FGP_NOWAIT. Yes, will propose a separate patch later on. > > This change seems correct but also will have runtime effects. What are > they? Other than a couple of extra cycles when idle page tracking is enabled, I didn't think of other effects. It should be negligible. The idle flag doesn't play a role in page reclaim algorithm, so it won't have impact on that.