From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 7E3F86B00EE for ; Thu, 11 Aug 2011 05:25:34 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 896743EE0B6 for ; Thu, 11 Aug 2011 18:25:31 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 707FB45DF49 for ; Thu, 11 Aug 2011 18:25:31 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 5737E45DF4E for ; Thu, 11 Aug 2011 18:25:31 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 3D9BD1DB8045 for ; Thu, 11 Aug 2011 18:25:31 +0900 (JST) Received: from m107.s.css.fujitsu.com (m107.s.css.fujitsu.com [10.240.81.147]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 660AB1DB8046 for ; Thu, 11 Aug 2011 18:25:25 +0900 (JST) Date: Thu, 11 Aug 2011 18:18:04 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 6/7] mm: vmscan: Throttle reclaim if encountering too many dirty pages under writeback Message-Id: <20110811181804.44f2ee80.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <1312973240-32576-7-git-send-email-mgorman@suse.de> References: <1312973240-32576-1-git-send-email-mgorman@suse.de> <1312973240-32576-7-git-send-email-mgorman@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 , Rik van Riel , Minchan Kim On Wed, 10 Aug 2011 11:47:19 +0100 Mel Gorman wrote: > Workloads that are allocating frequently and writing files place a > large number of dirty pages on the LRU. With use-once logic, it is > possible for them to reach the end of the LRU quickly requiring the > reclaimer to scan more to find clean pages. Ordinarily, processes that > are dirtying memory will get throttled by dirty balancing but this > is a global heuristic and does not take into account that LRUs are > maintained on a per-zone basis. This can lead to a situation whereby > reclaim is scanning heavily, skipping over a large number of pages > under writeback and recycling them around the LRU consuming CPU. > > This patch checks how many of the number of pages isolated from the > LRU were dirty and under writeback. If a percentage of them under > writeback, the process will be throttled if a backing device or the > zone is congested. Note that this applies whether it is anonymous or > file-backed pages that are under writeback meaning that swapping is > potentially throttled. This is intentional due to the fact if the > swap device is congested, scanning more pages and dispatching more > IO is not going to help matters. > > The percentage that must be in writeback depends on the priority. At > default priority, all of them must be dirty. At DEF_PRIORITY-1, 50% > of them must be, DEF_PRIORITY-2, 25% etc. i.e. as pressure increases > the greater the likelihood the process will get throttled to allow > the flusher threads to make some progress. > > Signed-off-by: Mel Gorman > Reviewed-by: Minchan Kim > Acked-by: Johannes Weiner Reviewed-by: KAMEZAWA Hiroyuki Maybe I need to add memcg_is_congested() ... -- 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