From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx126.postini.com [74.125.245.126]) by kanga.kvack.org (Postfix) with SMTP id 0D6586B0006 for ; Fri, 12 Apr 2013 16:52:52 -0400 (EDT) Date: Fri, 12 Apr 2013 21:41:50 +0100 From: Mel Gorman Subject: Re: [PATCH 0/10] Reduce system disruption due to kswapd V2 Message-ID: <20130412204129.GA13146@suse.de> References: <1365505625-9460-1-git-send-email-mgorman@suse.de> <51672331.6070605@bitsync.net> <20130412193947.GJ11656@suse.de> <5168699A.40407@bitsync.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <5168699A.40407@bitsync.net> Sender: owner-linux-mm@kvack.org List-ID: To: Zlatko Calusic Cc: Andrew Morton , Jiri Slaby , Valdis Kletnieks , Rik van Riel , Johannes Weiner , dormando , Satoru Moriya , Michal Hocko , Linux-MM , LKML On Fri, Apr 12, 2013 at 10:07:54PM +0200, Zlatko Calusic wrote: > On 12.04.2013 21:40, Mel Gorman wrote: > >On Thu, Apr 11, 2013 at 10:55:13PM +0200, Zlatko Calusic wrote: > >>On 09.04.2013 13:06, Mel Gorman wrote: > >> > >> > >>- The only slightly negative thing I observed is that with the patch > >>applied kswapd burns 10x - 20x more CPU. So instead of about 15 > >>seconds, it has now spent more than 4 minutes on one particular > >>machine with a quite steady load (after about 12 days of uptime). > >>Admittedly, that's still nothing too alarming, but... > >> > > > >Would you happen to know what circumstances trigger the higher CPU > >usage? > > > > Really nothing special. The server is lightly loaded, but it does > enough reading from the disk so that pagecache is mostly populated > and page reclaiming is active. So, kswapd is no doubt using CPU time > gradually, nothing extraordinary. > > When I sent my reply yesterday, the server uptime was 12 days, and > kswapd had accumulated 4:28 CPU time. Now, approx 24 hours later (13 > days uptime): > > root 23 0.0 0.0 0 0 ? S Mar30 4:52 [kswapd0] > Ok, that's not too crazy. > I will apply your v3 series soon and see if there's any improvement > wrt CPU usage, although as I said I don't see that as a big issue. > It's still only 0.013% of available CPU resources (dual core CPU). > Excellent, thanks very much for testing and reporting back. I read your mail on the zone balancing and FWIW I would not have expected this series to have any impact on it. I do not have a good theory yet as to what the problem is but I'll give it some thought and se what I come up with. I'll be at LSF/MM next week so it might take me a while. -- Mel Gorman SUSE Labs -- 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