From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966005Ab2EQNO6 (ORCPT ); Thu, 17 May 2012 09:14:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:15484 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965253Ab2EQNO5 (ORCPT ); Thu, 17 May 2012 09:14:57 -0400 Message-ID: <4FB4F999.4010008@redhat.com> Date: Thu, 17 May 2012 09:14:01 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Michal Hocko CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Andrew Morton , Mel Gorman , Minchan Kim , KAMEZAWA Hiroyuki Subject: Re: [PATCH] mm: consider all swapped back pages in used-once logic References: <1337246033-13719-1-git-send-email-mhocko@suse.cz> In-Reply-To: <1337246033-13719-1-git-send-email-mhocko@suse.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/17/2012 05:13 AM, Michal Hocko wrote: > [64574746 vmscan: detect mapped file pages used only once] made mapped pages > have another round in inactive list because they might be just short > lived and so we could consider them again next time. This heuristic > helps to reduce pressure on the active list with a streaming IO > worklods. > This patch fixes a regression introduced by this commit for heavy shmem > based workloads because unlike Anon pages, which are excluded from this > heuristic because they are usually long lived, shmem pages are handled > as a regular page cache. > This doesn't work quite well, unfortunately, if the workload is mostly > backed by shmem (in memory database sitting on 80% of memory) with a > streaming IO in the background (backup - up to 20% of memory). Anon > inactive list is full of (dirty) shmem pages when watermarks are > hit. Shmem pages are kept in the inactive list (they are referenced) > in the first round and it is hard to reclaim anything else so we reach > lower scanning priorities very quickly which leads to an excessive swap > out. > > Let's fix this by excluding all swap backed pages (they tend to be long > lived wrt. the regular page cache anyway) from used-once heuristic and > rather activate them if they are referenced. > > CC: Johannes Weiner > CC: Andrew Morton > CC: Mel Gorman > CC: Minchan Kim > CC: KAMEZAWA Hiroyuki > CC: Rik van Riel > CC: stable [2.6.34+] > Signed-off-by: Michal Hocko Reviewed-by: Rik van Riel -- All rights reversed From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx155.postini.com [74.125.245.155]) by kanga.kvack.org (Postfix) with SMTP id 0FDE96B0083 for ; Thu, 17 May 2012 09:14:33 -0400 (EDT) Message-ID: <4FB4F999.4010008@redhat.com> Date: Thu, 17 May 2012 09:14:01 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] mm: consider all swapped back pages in used-once logic References: <1337246033-13719-1-git-send-email-mhocko@suse.cz> In-Reply-To: <1337246033-13719-1-git-send-email-mhocko@suse.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , Andrew Morton , Mel Gorman , Minchan Kim , KAMEZAWA Hiroyuki On 05/17/2012 05:13 AM, Michal Hocko wrote: > [64574746 vmscan: detect mapped file pages used only once] made mapped pages > have another round in inactive list because they might be just short > lived and so we could consider them again next time. This heuristic > helps to reduce pressure on the active list with a streaming IO > worklods. > This patch fixes a regression introduced by this commit for heavy shmem > based workloads because unlike Anon pages, which are excluded from this > heuristic because they are usually long lived, shmem pages are handled > as a regular page cache. > This doesn't work quite well, unfortunately, if the workload is mostly > backed by shmem (in memory database sitting on 80% of memory) with a > streaming IO in the background (backup - up to 20% of memory). Anon > inactive list is full of (dirty) shmem pages when watermarks are > hit. Shmem pages are kept in the inactive list (they are referenced) > in the first round and it is hard to reclaim anything else so we reach > lower scanning priorities very quickly which leads to an excessive swap > out. > > Let's fix this by excluding all swap backed pages (they tend to be long > lived wrt. the regular page cache anyway) from used-once heuristic and > rather activate them if they are referenced. > > CC: Johannes Weiner > CC: Andrew Morton > CC: Mel Gorman > CC: Minchan Kim > CC: KAMEZAWA Hiroyuki > CC: Rik van Riel > CC: stable [2.6.34+] > Signed-off-by: Michal Hocko Reviewed-by: Rik van Riel -- All rights reversed -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org