From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f179.google.com (mail-wi0-f179.google.com [209.85.212.179]) by kanga.kvack.org (Postfix) with ESMTP id 0BD316B0032 for ; Tue, 9 Dec 2014 04:47:23 -0500 (EST) Received: by mail-wi0-f179.google.com with SMTP id ex7so1063730wid.0 for ; Tue, 09 Dec 2014 01:47:22 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u12si14062210wiv.10.2014.12.09.01.47.21 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 09 Dec 2014 01:47:21 -0800 (PST) Date: Tue, 9 Dec 2014 09:47:18 +0000 From: Mel Gorman Subject: Re: [RFC PATCH 2/3] mm: more aggressive page stealing for UNMOVABLE allocations Message-ID: <20141209094718.GA21903@suse.de> References: <1417713178-10256-1-git-send-email-vbabka@suse.cz> <1417713178-10256-3-git-send-email-vbabka@suse.cz> <20141209030939.GD3358@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20141209030939.GD3358@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Vlastimil Babka , linux-mm@kvack.org, Joonsoo Kim , linux-kernel@vger.kernel.org, Rik van Riel , David Rientjes On Tue, Dec 09, 2014 at 12:09:40PM +0900, Minchan Kim wrote: > On Thu, Dec 04, 2014 at 06:12:57PM +0100, Vlastimil Babka wrote: > > When allocation falls back to stealing free pages of another migratetype, > > it can decide to steal extra pages, or even the whole pageblock in order to > > reduce fragmentation, which could happen if further allocation fallbacks > > pick a different pageblock. In try_to_steal_freepages(), one of the situations > > where extra pages are stolen happens when we are trying to allocate a > > MIGRATE_RECLAIMABLE page. > > > > However, MIGRATE_UNMOVABLE allocations are not treated the same way, although > > spreading such allocation over multiple fallback pageblocks is arguably even > > worse than it is for RECLAIMABLE allocations. To minimize fragmentation, we > > should minimize the number of such fallbacks, and thus steal as much as is > > possible from each fallback pageblock. > > Fair enough. > Just to be absolutly sure, check that data and see what the number of MIGRATE_UNMOVABLE blocks looks like over time. Make sure it's not just continually growing. MIGRATE_RECLAIMABLE and MIGRATE_MOVABLE blocks were expected to be freed if the system was aggressively reclaimed but the same is not be true of MIGRATE_UNMOVABLE. Even if all processes are aggressively reclaimed for example, the page tables are still there. -- Mel Gorman SUSE Labs -- 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