From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx132.postini.com [74.125.245.132]) by kanga.kvack.org (Postfix) with SMTP id 7DCD86B0005 for ; Wed, 10 Apr 2013 02:48:34 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 8A0B43EE0C2 for ; Wed, 10 Apr 2013 15:48:32 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 704FA45DE53 for ; Wed, 10 Apr 2013 15:48:32 +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 506D845DE4F for ; Wed, 10 Apr 2013 15:48:32 +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 39C2A1DB8040 for ; Wed, 10 Apr 2013 15:48:32 +0900 (JST) Received: from m1000.s.css.fujitsu.com (m1000.s.css.fujitsu.com [10.240.81.136]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id DC17F1DB8037 for ; Wed, 10 Apr 2013 15:48:31 +0900 (JST) Message-ID: <51650B1F.1060607@jp.fujitsu.com> Date: Wed, 10 Apr 2013 15:47:59 +0900 From: Kamezawa Hiroyuki MIME-Version: 1.0 Subject: Re: [PATCH 01/10] mm: vmscan: Limit the number of pages kswapd reclaims at each priority References: <1365505625-9460-1-git-send-email-mgorman@suse.de> <1365505625-9460-2-git-send-email-mgorman@suse.de> In-Reply-To: <1365505625-9460-2-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , Jiri Slaby , Valdis Kletnieks , Rik van Riel , Zlatko Calusic , Johannes Weiner , dormando , Satoru Moriya , Michal Hocko , Linux-MM , LKML (2013/04/09 20:06), Mel Gorman wrote: > The number of pages kswapd can reclaim is bound by the number of pages it > scans which is related to the size of the zone and the scanning priority. In > many cases the priority remains low because it's reset every SWAP_CLUSTER_MAX > reclaimed pages but in the event kswapd scans a large number of pages it > cannot reclaim, it will raise the priority and potentially discard a large > percentage of the zone as sc->nr_to_reclaim is ULONG_MAX. The user-visible > effect is a reclaim "spike" where a large percentage of memory is suddenly > freed. It would be bad enough if this was just unused memory but because > of how anon/file pages are balanced it is possible that applications get > pushed to swap unnecessarily. > > This patch limits the number of pages kswapd will reclaim to the high > watermark. Reclaim will still overshoot due to it not being a hard limit as > shrink_lruvec() will ignore the sc.nr_to_reclaim at DEF_PRIORITY but it > prevents kswapd reclaiming the world at higher priorities. The number of > pages it reclaims is not adjusted for high-order allocations as kswapd will > reclaim excessively if it is to balance zones for high-order allocations. > > Signed-off-by: Mel Gorman > Reviewed-by: Rik van Riel > Acked-by: Johannes Weiner > Acked-by: KAMEZAWA Hiroyuki -- 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