From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx103.postini.com [74.125.245.103]) by kanga.kvack.org (Postfix) with SMTP id 4F3BB6B007E for ; Thu, 5 Apr 2012 17:46:22 -0400 (EDT) Received: by ghrr18 with SMTP id r18so1330737ghr.14 for ; Thu, 05 Apr 2012 14:46:21 -0700 (PDT) Date: Thu, 5 Apr 2012 14:46:17 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH 2/2] mm: compaction: allow isolation of lower order buddy pages In-Reply-To: <1333643534-1591-3-git-send-email-b.zolnierkie@samsung.com> Message-ID: References: <1333643534-1591-1-git-send-email-b.zolnierkie@samsung.com> <1333643534-1591-3-git-send-email-b.zolnierkie@samsung.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Bartlomiej Zolnierkiewicz Cc: linux-mm@kvack.org, mgorman@suse.de, Kyungmin Park On Thu, 5 Apr 2012, Bartlomiej Zolnierkiewicz wrote: > diff --git a/mm/compaction.c b/mm/compaction.c > index bc77135..642c17a 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -115,8 +115,8 @@ static bool suitable_migration_target(struct page *page) > if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE) > return false; > > - /* If the page is a large free page, then allow migration */ > - if (PageBuddy(page) && page_order(page) >= pageblock_order) > + /* If the page is a free page, then allow migration */ > + if (PageBuddy(page)) > return true; > > /* If the block is MIGRATE_MOVABLE, allow migration */ So when we try to allocate a 2M hugepage through the buddy allocator where the pageblock is also 2M, wouldn't this result in a lot of unnecessary migration of memory that may not end up defragmented enough for the allocation to succeed? Sounds like a regression for hugepage allocation. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org