From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752670AbcDZRYI (ORCPT ); Tue, 26 Apr 2016 13:24:08 -0400 Received: from mx2.suse.de ([195.135.220.15]:55762 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751870AbcDZRYG (ORCPT ); Tue, 26 Apr 2016 13:24:06 -0400 Subject: Re: [PATCH 19/28] mm, page_alloc: Reduce cost of fair zone allocation policy retry To: Mel Gorman , Andrew Morton References: <1460710760-32601-1-git-send-email-mgorman@techsingularity.net> <1460711275-1130-1-git-send-email-mgorman@techsingularity.net> <1460711275-1130-7-git-send-email-mgorman@techsingularity.net> Cc: Jesper Dangaard Brouer , Linux-MM , LKML From: Vlastimil Babka Message-ID: <571FA432.1050103@suse.cz> Date: Tue, 26 Apr 2016 19:24:02 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1 MIME-Version: 1.0 In-Reply-To: <1460711275-1130-7-git-send-email-mgorman@techsingularity.net> Content-Type: text/plain; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/15/2016 11:07 AM, Mel Gorman wrote: > The fair zone allocation policy is not without cost but it can be reduced > slightly. This patch removes an unnecessary local variable, checks the > likely conditions of the fair zone policy first, uses a bool instead of > a flags check and falls through when a remote node is encountered instead > of doing a full restart. The benefit is marginal but it's there > > 4.6.0-rc2 4.6.0-rc2 > decstat-v1r20 optfair-v1r20 > Min alloc-odr0-1 377.00 ( 0.00%) 380.00 ( -0.80%) > Min alloc-odr0-2 273.00 ( 0.00%) 273.00 ( 0.00%) > Min alloc-odr0-4 226.00 ( 0.00%) 227.00 ( -0.44%) > Min alloc-odr0-8 196.00 ( 0.00%) 196.00 ( 0.00%) > Min alloc-odr0-16 183.00 ( 0.00%) 183.00 ( 0.00%) > Min alloc-odr0-32 175.00 ( 0.00%) 173.00 ( 1.14%) > Min alloc-odr0-64 172.00 ( 0.00%) 169.00 ( 1.74%) > Min alloc-odr0-128 170.00 ( 0.00%) 169.00 ( 0.59%) > Min alloc-odr0-256 183.00 ( 0.00%) 180.00 ( 1.64%) > Min alloc-odr0-512 191.00 ( 0.00%) 190.00 ( 0.52%) > Min alloc-odr0-1024 199.00 ( 0.00%) 198.00 ( 0.50%) > Min alloc-odr0-2048 204.00 ( 0.00%) 204.00 ( 0.00%) > Min alloc-odr0-4096 210.00 ( 0.00%) 209.00 ( 0.48%) > Min alloc-odr0-8192 213.00 ( 0.00%) 213.00 ( 0.00%) > Min alloc-odr0-16384 214.00 ( 0.00%) 214.00 ( 0.00%) > > The benefit is marginal at best but one of the most important benefits, > avoiding a second search when falling back to another node is not triggered > by this particular test so the benefit for some corner cases is understated. > > Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka