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 B0B7B6B00EE for ; Wed, 31 Aug 2011 08:31:00 -0400 (EDT) Date: Wed, 31 Aug 2011 14:30:51 +0200 From: Johannes Weiner Subject: Re: [patch] memcg: skip scanning active lists based on individual size Message-ID: <20110831123051.GA18081@redhat.com> References: <20110831090850.GA27345@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Andrew Morton , Rik van Riel , KOSAKI Motohiro , KAMEZAWA Hiroyuki , Daisuke Nishimura , Balbir Singh , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Wed, Aug 31, 2011 at 07:13:34PM +0900, Minchan Kim wrote: > On Wed, Aug 31, 2011 at 6:08 PM, Johannes Weiner wrote: > > Reclaim decides to skip scanning an active list when the corresponding > > inactive list is above a certain size in comparison to leave the > > assumed working set alone while there are still enough reclaim > > candidates around. > > > > The memcg implementation of comparing those lists instead reports > > whether the whole memcg is low on the requested type of inactive > > pages, considering all nodes and zones. > > > > This can lead to an oversized active list not being scanned because of > > the state of the other lists in the memcg, as well as an active list > > being scanned while its corresponding inactive list has enough pages. > > > > Not only is this wrong, it's also a scalability hazard, because the > > global memory state over all nodes and zones has to be gathered for > > each memcg and zone scanned. > > > > Make these calculations purely based on the size of the two LRU lists > > that are actually affected by the outcome of the decision. > > > > Signed-off-by: Johannes Weiner > > Cc: Rik van Riel > > Cc: KOSAKI Motohiro > > Cc: KAMEZAWA Hiroyuki > > Cc: Daisuke Nishimura > > Cc: Balbir Singh > > Reviewed-by: Minchan Kim Thank you. > I can't understand why memcg is designed for considering all nodes and zones. > Is it a mistake or on purpose? > Maybe Kame or Balbir can answer it. > > Anyway, this change does make sense to me. > > Nitpick: Please remove inactive_ratio in Documentation/cgroups/memory.txt. > I think it would be better to separate it into another patch. Good catch. --- Subject: [patch] memcg: skip scanning active lists based on individual fix Also ditch the documentation note for the removed stats value. Signed-off-by: Johannes Weiner --- diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt index 06eb6d9..cc0ebc5 100644 --- a/Documentation/cgroups/memory.txt +++ b/Documentation/cgroups/memory.txt @@ -418,7 +418,6 @@ total_unevictable - sum of all children's "unevictable" # The following additional stats are dependent on CONFIG_DEBUG_VM. -inactive_ratio - VM internal parameter. (see mm/page_alloc.c) recent_rotated_anon - VM internal parameter. (see mm/vmscan.c) recent_rotated_file - VM internal parameter. (see mm/vmscan.c) recent_scanned_anon - VM internal parameter. (see mm/vmscan.c) -- 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