Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754763Ab2EXJQO (ORCPT ); Thu, 24 May 2012 05:16:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:12482 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754023Ab2EXJQM (ORCPT ); Thu, 24 May 2012 05:16:12 -0400 Message-ID: <4FBDFC43.6040707@redhat.com> Date: Thu, 24 May 2012 11:15:47 +0200 From: Jerome Marchand User-Agent: Mozilla/5.0 (X11; Linux i686; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Satoru Moriya CC: Andrew Morton , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Rik van Riel , "lwoodman@redhat.com" , "jweiner@redhat.com" , KOSAKI Motohiro , Richard Davies , Seiji Aguchi , "dle-develop@lists.sourceforge.net" , Minchan Kim , Christoph Lameter Subject: Re: [PATCH RESEND] avoid swapping out with swappiness==0 References: <65795E11DBF1E645A09CEC7EAEE94B9C015A48DF62@USINDEVS02.corp.hds.com> In-Reply-To: <65795E11DBF1E645A09CEC7EAEE94B9C015A48DF62@USINDEVS02.corp.hds.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2446 Lines: 67 On 05/23/2012 10:41 PM, Satoru Moriya wrote: > Hi Andrew, > > This patch has been reviewed for couple of months. > > This patch *only* improves the behavior when the kernel has > enough filebacked pages. It means that it does not change > the behavior when kernel has small number of filebacked pages. > > Kosaki-san pointed out that the threshold which we use > to decide whether filebacked page is enough or not is not > appropriate(*). > > (*) http://www.spinics.net/lists/linux-mm/msg32380.html > > As I described in (**), I believe that threshold discussion > should be done in other thread because it affects not only > swappiness=0 case and the kernel behave the same way with > or without this patch below the threshold. > > (**) http://www.spinics.net/lists/linux-mm/msg34317.html > > The patch may not be perfect but, at least, we can improve > the kernel behavior in the enough filebacked memory case > with this patch. I believe it's better than nothing. > > Do you have any comments about it? > > NOTE: I updated the patch with Acked-by tags > > --- > Sometimes we'd like to avoid swapping out anonymous memory > in particular, avoid swapping out pages of important process or > process groups while there is a reasonable amount of pagecache > on RAM so that we can satisfy our customers' requirements. > > OTOH, we can control how aggressive the kernel will swap memory pages > with /proc/sys/vm/swappiness for global and > /sys/fs/cgroup/memory/memory.swappiness for each memcg. > > But with current reclaim implementation, the kernel may swap out > even if we set swappiness==0 and there is pagecache on RAM. > > This patch changes the behavior with swappiness==0. If we set > swappiness==0, the kernel does not swap out completely > (for global reclaim until the amount of free pages and filebacked > pages in a zone has been reduced to something very very small > (nr_free + nr_filebacked < high watermark)). > > Any comments are welcome. > > Regards, > Satoru Moriya > > Signed-off-by: Satoru Moriya > Acked-by: Minchan Kim > Acked-by: Rik van Riel > Acked-by: Jerome Marchand -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/