From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 142246B00EE for ; Thu, 11 Aug 2011 14:19:08 -0400 (EDT) Message-ID: <4E441D0E.6020602@redhat.com> Date: Thu, 11 Aug 2011 14:18:54 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH 5/7] mm: vmscan: Do not writeback filesystem pages in kswapd except in high priority References: <1312973240-32576-1-git-send-email-mgorman@suse.de> <1312973240-32576-6-git-send-email-mgorman@suse.de> In-Reply-To: <1312973240-32576-6-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Linux-MM , LKML , XFS , Dave Chinner , Christoph Hellwig , Johannes Weiner , Wu Fengguang , Jan Kara , Minchan Kim On 08/10/2011 06:47 AM, Mel Gorman wrote: > It is preferable that no dirty pages are dispatched for cleaning from > the page reclaim path. At normal priorities, this patch prevents kswapd > writing pages. > > However, page reclaim does have a requirement that pages be freed > in a particular zone. If it is failing to make sufficient progress > (reclaiming< SWAP_CLUSTER_MAX at any priority priority), the priority > is raised to scan more pages. A priority of DEF_PRIORITY - 3 is > considered to be the point where kswapd is getting into trouble > reclaiming pages. If this priority is reached, kswapd will dispatch > pages for writing. > > Signed-off-by: Mel Gorman > Reviewed-by: Minchan Kim My only worry with this patch is that maybe we'll burn too much CPU time freeing pages from a zone. However, chances are we'll have freed pages from other zones when scanning one zone multiple times (the page cache dirty limit is global, the clean pages have to be _somewhere_). Since the bulk of the allocators are not too picky about which zone they get their pages from, I suspect this patch will be an overall improvement pretty much all the time. Acked-by: Rik van Riel -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org