Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751789AbaBGJVH (ORCPT ); Fri, 7 Feb 2014 04:21:07 -0500 Received: from cantor2.suse.de ([195.135.220.15]:32855 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750868AbaBGJVC (ORCPT ); Fri, 7 Feb 2014 04:21:02 -0500 Message-ID: <52F4A579.7040009@suse.cz> Date: Fri, 07 Feb 2014 10:20:57 +0100 From: Vlastimil Babka User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Joonsoo Kim , Andrew Morton CC: Mel Gorman , Joonsoo Kim , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/5] mm/compaction: disallow high-order page for migration target References: <1391749726-28910-1-git-send-email-iamjoonsoo.kim@lge.com> <1391749726-28910-2-git-send-email-iamjoonsoo.kim@lge.com> In-Reply-To: <1391749726-28910-2-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/07/2014 06:08 AM, Joonsoo Kim wrote: > Purpose of compaction is to get a high order page. Currently, if we find > high-order page while searching migration target page, we break it to > order-0 pages and use them as migration target. It is contrary to purpose > of compaction, so disallow high-order page to be used for > migration target. I guess this actually didn't trigger often because with large free blocks available, compaction shouldn't even be running (unless started manually). But the change makes sense. > Additionally, clean-up logic in suitable_migration_target() to simply. simply -> simplify the code. > There is no functional changes from this clean-up. > > Signed-off-by: Joonsoo Kim Acked-by: Vlastimil Babka > diff --git a/mm/compaction.c b/mm/compaction.c > index 3a91a2e..bbe1260 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -217,21 +217,12 @@ static inline bool compact_trylock_irqsave(spinlock_t *lock, > /* Returns true if the page is within a block suitable for migration to */ > static bool suitable_migration_target(struct page *page) > { > - int migratetype = get_pageblock_migratetype(page); > - > - /* Don't interfere with memory hot-remove or the min_free_kbytes blocks */ > - if (migratetype == MIGRATE_RESERVE) > - return false; > - > - if (is_migrate_isolate(migratetype)) > - return false; > - > - /* If the page is a large free page, then allow migration */ > + /* If the page is a large free page, then disallow migration */ > if (PageBuddy(page) && page_order(page) >= pageblock_order) > - return true; > + return false; > > /* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */ > - if (migrate_async_suitable(migratetype)) > + if (migrate_async_suitable(get_pageblock_migratetype(page))) > return true; > > /* Otherwise skip the block */ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/