From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757544Ab3HONls (ORCPT ); Thu, 15 Aug 2013 09:41:48 -0400 Received: from mail-pb0-f45.google.com ([209.85.160.45]:64814 "EHLO mail-pb0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756322Ab3HONlr (ORCPT ); Thu, 15 Aug 2013 09:41:47 -0400 Date: Thu, 15 Aug 2013 22:41:39 +0900 From: Minchan Kim To: Mel Gorman Cc: Hillf Danton , LKML , Linux-MM Subject: Re: kswapd skips compaction if reclaim order drops to zero? Message-ID: <20130815134139.GC8437@gmail.com> References: <20130815104727.GT2296@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130815104727.GT2296@suse.de> 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 Hey Mel, On Thu, Aug 15, 2013 at 11:47:27AM +0100, Mel Gorman wrote: > On Thu, Aug 15, 2013 at 06:02:53PM +0800, Hillf Danton wrote: > > If the allocation order is not high, direct compaction does nothing. > > Can we skip compaction here if order drops to zero? > > > > If the allocation order is not high then > > pgdat_needs_compaction == (order > 0) == false == no calling compact_pdatt > > In the case where order is reset to 0 due to fragmentation then it does > call compact_pgdat but it does no work due to the cc->order check in > __compact_pgdat. > I am looking at mmotm-2013-08-07-16-55 but couldn't find cc->order check right before compact_zone in __comact_pgdat. Could you pinpoint code piece? > -- > 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 -- Kind regards, Minchan Kim