Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754556Ab3CXTAO (ORCPT ); Sun, 24 Mar 2013 15:00:14 -0400 Received: from mail-ea0-f171.google.com ([209.85.215.171]:43750 "EHLO mail-ea0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754062Ab3CXTAM (ORCPT ); Sun, 24 Mar 2013 15:00:12 -0400 Message-ID: <514F4D37.5030304@suse.cz> Date: Sun, 24 Mar 2013 20:00:07 +0100 From: Jiri Slaby User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:19.0) Gecko/20130124 Thunderbird/19.0 MIME-Version: 1.0 To: Mel Gorman , Linux-MM CC: Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Satoru Moriya , Michal Hocko , LKML Subject: Re: [RFC PATCH 0/8] Reduce system disruption due to kswapd References: <1363525456-10448-1-git-send-email-mgorman@suse.de> In-Reply-To: <1363525456-10448-1-git-send-email-mgorman@suse.de> X-Enigmail-Version: 1.6a1pre Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1858 Lines: 39 On 03/17/2013 02:04 PM, Mel Gorman wrote: > Kswapd and page reclaim behaviour has been screwy in one way or the other > for a long time. Very broadly speaking it worked in the far past because > machines were limited in memory so it did not have that many pages to scan > and it stalled congestion_wait() frequently to prevent it going completely > nuts. In recent times it has behaved very unsatisfactorily with some of > the problems compounded by the removal of stall logic and the introduction > of transparent hugepage support with high-order reclaims. > > There are many variations of bugs that are rooted in this area. One example > is reports of a large copy operations or backup causing the machine to > grind to a halt or applications pushed to swap. Sometimes in low memory > situations a large percentage of memory suddenly gets reclaimed. In other > cases an application starts and kswapd hits 100% CPU usage for prolonged > periods of time and so on. There is now talk of introducing features like > an extra free kbytes tunable to work around aspects of the problem instead > of trying to deal with it. It's compounded by the problem that it can be > very workload and machine specific. > > This RFC is aimed at investigating if kswapd can be address these various > problems in a relatively straight-forward fashion without a fundamental > rewrite. > > Patches 1-2 limits the number of pages kswapd reclaims while still obeying > the anon/file proportion of the LRUs it should be scanning. Hi, patch 1 does not apply (on the top of -next), so I can't test this :(. thanks, -- js suse labs -- 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/