From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755613Ab2LLWeD (ORCPT ); Wed, 12 Dec 2012 17:34:03 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42007 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754245Ab2LLWeB (ORCPT ); Wed, 12 Dec 2012 17:34:01 -0500 Message-ID: <50C905CE.1010405@redhat.com> Date: Wed, 12 Dec 2012 17:31:42 -0500 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: Johannes Weiner CC: Andrew Morton , Michal Hocko , Mel Gorman , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch 7/8] mm: vmscan: compaction works against zones, not lruvecs References: <1355348620-9382-1-git-send-email-hannes@cmpxchg.org> <1355348620-9382-8-git-send-email-hannes@cmpxchg.org> In-Reply-To: <1355348620-9382-8-git-send-email-hannes@cmpxchg.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12/2012 04:43 PM, Johannes Weiner wrote: > The restart logic for when reclaim operates back to back with > compaction is currently applied on the lruvec level. But this does > not make sense, because the container of interest for compaction is a > zone as a whole, not the zone pages that are part of a certain memory > cgroup. > > Negative impact is bounded. For one, the code checks that the lruvec > has enough reclaim candidates, so it does not risk getting stuck on a > condition that can not be fulfilled. And the unfairness of hammering > on one particular memory cgroup to make progress in a zone will be > amortized by the round robin manner in which reclaim goes through the > memory cgroups. Still, this can lead to unnecessary allocation > latencies when the code elects to restart on a hard to reclaim or > small group when there are other, more reclaimable groups in the zone. > > Move this logic to the zone level and restart reclaim for all memory > cgroups in a zone when compaction requires more free pages from it. > > Signed-off-by: Johannes Weiner Reviewed-by: Rik van Riel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx131.postini.com [74.125.245.131]) by kanga.kvack.org (Postfix) with SMTP id A027A6B009F for ; Wed, 12 Dec 2012 17:33:16 -0500 (EST) Message-ID: <50C905CE.1010405@redhat.com> Date: Wed, 12 Dec 2012 17:31:42 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [patch 7/8] mm: vmscan: compaction works against zones, not lruvecs References: <1355348620-9382-1-git-send-email-hannes@cmpxchg.org> <1355348620-9382-8-git-send-email-hannes@cmpxchg.org> In-Reply-To: <1355348620-9382-8-git-send-email-hannes@cmpxchg.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , Michal Hocko , Mel Gorman , Hugh Dickins , linux-mm@kvack.org, linux-kernel@vger.kernel.org On 12/12/2012 04:43 PM, Johannes Weiner wrote: > The restart logic for when reclaim operates back to back with > compaction is currently applied on the lruvec level. But this does > not make sense, because the container of interest for compaction is a > zone as a whole, not the zone pages that are part of a certain memory > cgroup. > > Negative impact is bounded. For one, the code checks that the lruvec > has enough reclaim candidates, so it does not risk getting stuck on a > condition that can not be fulfilled. And the unfairness of hammering > on one particular memory cgroup to make progress in a zone will be > amortized by the round robin manner in which reclaim goes through the > memory cgroups. Still, this can lead to unnecessary allocation > latencies when the code elects to restart on a hard to reclaim or > small group when there are other, more reclaimable groups in the zone. > > Move this logic to the zone level and restart reclaim for all memory > cgroups in a zone when compaction requires more free pages from it. > > Signed-off-by: Johannes Weiner Reviewed-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/ . Don't email: email@kvack.org