From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755630AbdKBNJq (ORCPT ); Thu, 2 Nov 2017 09:09:46 -0400 Received: from outbound-smtp13.blacknight.com ([46.22.139.230]:36307 "EHLO outbound-smtp13.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754894AbdKBNJp (ORCPT ); Thu, 2 Nov 2017 09:09:45 -0400 Date: Thu, 2 Nov 2017 13:09:43 +0000 From: Mel Gorman To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Rientjes , Joonsoo Kim Subject: Re: [PATCH 2/3] mm, compaction: split off flag for not updating skip hints Message-ID: <20171102130943.7dpbuecrywtloein@techsingularity.net> References: <20171102121706.21504-1-vbabka@suse.cz> <20171102121706.21504-2-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20171102121706.21504-2-vbabka@suse.cz> User-Agent: NeoMutt/20170421 (1.8.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 02, 2017 at 01:17:05PM +0100, Vlastimil Babka wrote: > Pageblock skip hints were added as a heuristic for compaction, which shares > core code with CMA. Since CMA reliability would suffer from the heuristics, > compact_control flag ignore_skip_hint was added for the CMA use case. > Since commit 6815bf3f233e ("mm/compaction: respect ignore_skip_hint in > update_pageblock_skip") the flag also means that CMA won't *update* the skip > hints in addition to ignoring them. > > Today, direct compaction can also ignore the skip hints in the last resort > attempt, but there's no reason not to set them when isolation fails in such > case. Thus, this patch splits off a new no_set_skip_hint flag to avoid the > updating, which only CMA sets. This should improve the heuristics a bit, and > allow us to simplify the persistent skip bit handling as the next step. > > Signed-off-by: Vlastimil Babka Acked-by: Mel Gorman -- Mel Gorman SUSE Labs