From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161091AbcFQMHK (ORCPT ); Fri, 17 Jun 2016 08:07:10 -0400 Received: from outbound-smtp06.blacknight.com ([81.17.249.39]:40716 "EHLO outbound-smtp06.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755482AbcFQMHI (ORCPT ); Fri, 17 Jun 2016 08:07:08 -0400 Date: Fri, 17 Jun 2016 13:07:03 +0100 From: Mel Gorman To: Vlastimil Babka Cc: Andrew Morton , Linux-MM , Rik van Riel , Johannes Weiner , LKML , Michal Hocko Subject: Re: [PATCH 24/27] mm, page_alloc: Remove fair zone allocation policy Message-ID: <20160617120703.GN1868@techsingularity.net> References: <1465495483-11855-1-git-send-email-mgorman@techsingularity.net> <1465495483-11855-25-git-send-email-mgorman@techsingularity.net> <9f30977a-ff07-d783-4c21-e13bd2478aa3@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <9f30977a-ff07-d783-4c21-e13bd2478aa3@suse.cz> 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 Fri, Jun 17, 2016 at 01:27:09PM +0200, Vlastimil Babka wrote: > On 06/09/2016 08:04 PM, Mel Gorman wrote: > >The fair zone allocation policy interleaves allocation requests between > >zones to avoid an age inversion problem whereby new pages are reclaimed > >to balance a zone. Reclaim is now node-based so this should no longer be > >an issue and the fair zone allocation policy is not free. This patch > >removes it. > > I wonder if fair zone allocation had the side effect of preventing e.g. a > small Normal zone to be almost fully occupied by long-lived unreclaimable > allocations early in the kernel lifetime. So that might be one thing to > watch out for. It's a marginal corner case and the zonelist scan is slightly inefficient as the first zone is always skipped but the impact is light. > But otherwise I would agree it should be no longer needed > with node-based reclaim. > > >Signed-off-by: Mel Gorman > > Acked-by: Vlastimil Babka > Thanks. -- Mel Gorman SUSE Labs