Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757477Ab1E3QOY (ORCPT ); Mon, 30 May 2011 12:14:24 -0400 Received: from mail-pv0-f174.google.com ([74.125.83.174]:60909 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757156Ab1E3QOX (ORCPT ); Mon, 30 May 2011 12:14:23 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=fjGrAWZv9c8HBg03c/CocY4H00euw1aEV+w/RxrtjtbPz5x8GgFR8ENt7UQuisMft1 2j5uRJfxX+16CLkVexH3WBYFZWZYQT68ydCRxcuGajStLenS/D9cK1NaJKWZKaK1gbzH f6Ooj2ba+kjUCLZJIbfEmVfr1ez9q4Yu+G2yo= Date: Tue, 31 May 2011 01:14:15 +0900 From: Minchan Kim To: Mel Gorman 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: <20110530161415.GB2200@barrios-laptop> References: <20110530131300.GQ5044@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110530131300.GQ5044@csn.ul.ie> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2223 Lines: 56 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 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. -- Kind regards Minchan Kim -- 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/