From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx158.postini.com [74.125.245.158]) by kanga.kvack.org (Postfix) with SMTP id 6C4F06B0006 for ; Tue, 12 Mar 2013 12:52:52 -0400 (EDT) Date: Tue, 12 Mar 2013 12:52:47 -0400 From: Johannes Weiner Subject: Re: Swap defragging Message-ID: <20130312165247.GB1953@cmpxchg.org> References: <20130308023511.GD23767@cmpxchg.org> <513A97C5.7020008@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <513A97C5.7020008@gmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Will Huck Cc: Raymond Jennings , Linux Memory Management List On Sat, Mar 09, 2013 at 10:00:37AM +0800, Will Huck wrote: > Hi Johannes, > On 03/08/2013 10:35 AM, Johannes Weiner wrote: > >On Thu, Mar 07, 2013 at 06:07:23PM -0800, Raymond Jennings wrote: > >>Just a two cent question, but is there any merit to having the kernel > >>defragment swap space? > >That is a good question. > > > >Swap does fragment quite a bit, and there are several reasons for > >that. > > Are there any tools to test and monitor swap subsystem and page > reclaim subsystem? seekwatcher is great to see the IO patterns. Anything that uses anonymous memory can test swap: a java job, multiplying matrixes, kernel builds etc. I mostly log /proc/vmstat by taking snapshots at a regular interval during the workload, then plot and visually correlate the swapin/swapout counters with the individual LRU sizes, page fault rate, what have you, to get a feeling for what it's doing. -- 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