Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758360Ab1EaIcX (ORCPT ); Tue, 31 May 2011 04:32:23 -0400 Received: from gir.skynet.ie ([193.1.99.77]:59654 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756577Ab1EaIcV (ORCPT ); Tue, 31 May 2011 04:32:21 -0400 Date: Tue, 31 May 2011 09:32:15 +0100 From: Mel Gorman To: Minchan Kim Cc: akpm@linux-foundation.org, Ury Stankevich , KOSAKI Motohiro , Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@kernel.org Subject: Re: [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous Message-ID: <20110531083215.GT5044@csn.ul.ie> References: <20110530131300.GQ5044@csn.ul.ie> <20110530161415.GB2200@barrios-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20110530161415.GB2200@barrios-laptop> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2522 Lines: 64 On Tue, May 31, 2011 at 01:14:15AM +0900, Minchan Kim wrote: > On Mon, May 30, 2011 at 02:13:00PM +0100, Mel Gorman wrote: > > Asynchronous compaction is used when promoting to huge pages. This is > > all very nice but if there are a number of processes in compacting > > memory, a large number of pages can be isolated. An "asynchronous" > > process can stall for long periods of time as a result with a user > > reporting that firefox can stall for 10s of seconds. This patch aborts > > asynchronous compaction if too many pages are isolated as it's better to > > fail a hugepage promotion than stall a process. > > > > If accepted, this should also be considered for 2.6.39-stable. It should > > also be considered for 2.6.38-stable but ideally [11bc82d6: mm: > > compaction: Use async migration for __GFP_NO_KSWAPD and enforce no > > writeback] would be applied to 2.6.38 before consideration. > > > > Reported-and-Tested-by: Ury Stankevich > > Signed-off-by: Mel Gorman > Reviewed-by: Minchan Kim > Thanks > I have a nitpick below. > Otherwise, looks good to me. > > > --- > > mm/compaction.c | 32 ++++++++++++++++++++++++++------ > > 1 files changed, 26 insertions(+), 6 deletions(-) > > > > diff --git a/mm/compaction.c b/mm/compaction.c > > index 021a296..331a2ee 100644 > > --- a/mm/compaction.c > > +++ b/mm/compaction.c > > @@ -240,11 +240,20 @@ static bool too_many_isolated(struct zone *zone) > > return isolated > (inactive + active) / 2; > > } > > > > +/* possible outcome of isolate_migratepages */ > > +typedef enum { > > + ISOLATE_ABORT, /* Abort compaction now */ > > + ISOLATE_NONE, /* No pages isolated, continue scanning */ > > + ISOLATE_SUCCESS, /* Pages isolated, migrate */ > > +} isolate_migrate_t; > > + > > /* > > * Isolate all pages that can be migrated from the block pointed to by > > * the migrate scanner within compact_control. > > + * > > + * Returns false if compaction should abort at this point due to congestion. > > false? I think it would be better to use explicit word, ISOLATE_ABORT. > Oops, thanks for pointing that out. I'll post a V2 once it has been figured out why NR_ISOLATE_* is getting screwed up on !CONFIG_SMP. -- Mel Gorman SUSE Labs -- 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/