From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx194.postini.com [74.125.245.194]) by kanga.kvack.org (Postfix) with SMTP id 9F59E6B0032 for ; Mon, 22 Apr 2013 02:43:48 -0400 (EDT) Received: by mail-ie0-f173.google.com with SMTP id k5so6663035iea.4 for ; Sun, 21 Apr 2013 23:43:47 -0700 (PDT) Message-ID: <5174DC17.6000809@gmail.com> Date: Mon, 22 Apr 2013 14:43:35 +0800 From: Simon Jeons MIME-Version: 1.0 Subject: Re: [PATCH 0/10] Reduce system disruption due to kswapd V2 References: <1365505625-9460-1-git-send-email-mgorman@suse.de> <51672331.6070605@bitsync.net> <20130412193947.GJ11656@suse.de> <5168699A.40407@bitsync.net> <5174DA8F.2020400@bitsync.net> In-Reply-To: <5174DA8F.2020400@bitsync.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Zlatko Calusic Cc: Mel Gorman , Andrew Morton , Jiri Slaby , Valdis Kletnieks , Rik van Riel , Johannes Weiner , dormando , Satoru Moriya , Michal Hocko , Linux-MM , LKML Hi Zlatko, On 04/22/2013 02:37 PM, Zlatko Calusic wrote: > On 12.04.2013 22:07, 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] >> >> 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). >> > > JFTR, v3 kswapd uses about 15% more CPU time than v2. 2:50 kswapd CPU > time after 6 days 14h uptime. > > And find attached another debugging graph that shows how ANON pages > are privileged in the ZONE_NORMAL on a 4GB machine. Take notice that > the number of pages in the ZONE_DMA32 is scaled (/5) to fit the graph > nicely. > Could you tell me how you draw this picture? -- 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