From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx133.postini.com [74.125.245.133]) by kanga.kvack.org (Postfix) with SMTP id 2E19B6B0034 for ; Sat, 27 Apr 2013 03:10:38 -0400 (EDT) Received: by mail-pd0-f174.google.com with SMTP id y13so2425057pdi.33 for ; Sat, 27 Apr 2013 00:10:37 -0700 (PDT) Message-ID: <517B79E6.5050204@gmail.com> Date: Sat, 27 Apr 2013 15:10:30 +0800 From: Simon Jeons MIME-Version: 1.0 Subject: Re: [question] call mark_page_accessed() in minor fault References: <20130423122542.GA5638@gmail.com> <5176866A.2060400@openvz.org> <20130423134935.GA10138@gmail.com> In-Reply-To: <20130423134935.GA10138@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Zheng Liu Cc: Konstantin Khlebnikov , linux-mm@kvack.org, muming.wq@taobao.com Hi Zheng, On 04/23/2013 09:49 PM, Zheng Liu wrote: > Hi Konstantin, > > On Tue, Apr 23, 2013 at 05:02:34PM +0400, Konstantin Khlebnikov wrote: >> Zheng Liu wrote: >>> Hi all, >>> >>> Recently we meet a performance regression about mmaped page. When we upgrade >>> our product system from 2.6.18 kernel to a latest kernel, such as 2.6.32 kernel, >>> we will find that mmaped pages are reclaimed very quickly. We found that when >>> we hit a minor fault mark_page_accessed() is called in 2.6.18 kernel, but in >>> 2.6.32 kernel we don't call mark_page_accesed(). This means that mmaped pages >>> in 2.6.18 kernel are activated and moved into active list. While in 2.6.32 >>> kernel mmaped pages are still kept in inactive list. >>> >>> So my question is why we call mark_page_accessed() in 2.6.18 kernel, but don't >>> call it in 2.6.32 kernel. Has any reason here? >> Behavior was changed in commit >> v2.6.28-6130-gbf3f3bc "mm: don't mark_page_accessed in fault path" > Thanks for pointing it out. > >> Please see also commits >> v3.2-4876-g34dbc67 "vmscan: promote shared file mapped pages" and > Yes, I will give it try. If I understand correctly, this commit is > useful for multi-processes program that access a shared mmaped page, > but that could not be useful for us because our program is multi-thread. What's the difference behavior between multi-processes and multi-thread in this case? > >> v3.2-4877-gc909e99 "vmscan: activate executable pages after first usage". > We have backported this patch, but it is useless. This commit only > tries to activate a executable page, but our mmaped pages aren't with > this flag. > > Additional question is that currently mmaped page is reclaimed too > quickly. I think maybe we need to adjust our page reclaim strategy to > balance number of pages between mmaped page and file page cache. Now > every time we access a page using read(2)/write(2), this page will be > touched. But after first time we touch a mmaped page, we never touch it > again except that this page is evicted. > > Regards, > - Zheng > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org