From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752642AbcFPHoT (ORCPT ); Thu, 16 Jun 2016 03:44:19 -0400 Received: from outbound-smtp09.blacknight.com ([46.22.139.14]:36215 "EHLO outbound-smtp09.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751246AbcFPHoS (ORCPT ); Thu, 16 Jun 2016 03:44:18 -0400 Date: Thu, 16 Jun 2016 08:44:13 +0100 From: Mel Gorman To: Vlastimil Babka Cc: Andrew Morton , Linux-MM , Rik van Riel , Johannes Weiner , LKML Subject: Re: [PATCH 05/27] mm, vmscan: Have kswapd only scan based on the highest requested zone Message-ID: <20160616074413.GE1868@techsingularity.net> References: <1465495483-11855-1-git-send-email-mgorman@techsingularity.net> <1465495483-11855-6-git-send-email-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 15, 2016 at 03:13:13PM +0200, Vlastimil Babka wrote: > On 06/09/2016 08:04 PM, Mel Gorman wrote: > >kswapd checks all eligible zones to see if they need balancing even if it was > >woken for a lower zone. This made sense when we reclaimed on a per-zone basis > >because we wanted to shrink zones fairly so avoid age-inversion problems. > > Now we reclaim a single lru, but still will skip over pages from the higher > zones than reclaim_idx, so this is not much different from per-zone basis > wrt age-inversion? > Yes, but it only applies in the case where the allocation request is zone restricted. Previously, even with fair zone allocation policy, we had problems with a high zone with recently allocated pages being reclaimed simply because the low watermark was reached. Think of bugs in the past where the normal zone was a small percentage of memory. -- Mel Gorman SUSE Labs