From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932284Ab0LNQIM (ORCPT ); Tue, 14 Dec 2010 11:08:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:10851 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751960Ab0LNQIK (ORCPT ); Tue, 14 Dec 2010 11:08:10 -0500 Date: Tue, 14 Dec 2010 17:06:37 +0100 From: Andrea Arcangeli To: Mel Gorman Cc: KOSAKI Motohiro , linux-mm@kvack.org, Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, Marcelo Tosatti , Adam Litke , Avi Kivity , Hugh Dickins , Rik van Riel , Dave Hansen , Benjamin Herrenschmidt , Ingo Molnar , Mike Travis , KAMEZAWA Hiroyuki , Christoph Lameter , Chris Wright , bpicco@redhat.com, Balbir Singh , "Michael S. Tsirkin" , Peter Zijlstra , Johannes Weiner , Daisuke Nishimura , Chris Mason , Borislav Petkov Subject: Re: [PATCH 55 of 66] select CONFIG_COMPACTION if TRANSPARENT_HUGEPAGE enabled Message-ID: <20101214160637.GB5638@random.random> References: <89a62752012298bb500c.1288798110@v2.random> <20101109151756.BC7B.A69D9226@jp.fujitsu.com> <20101109211145.GB6809@random.random> <20101118162245.GE8135@csn.ul.ie> <20101209190407.GJ19131@random.random> <20101214094556.GF13914@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101214094556.GF13914@csn.ul.ie> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mel, On Tue, Dec 14, 2010 at 09:45:56AM +0000, Mel Gorman wrote: > On Thu, Dec 09, 2010 at 08:04:07PM +0100, Andrea Arcangeli wrote: > > On Thu, Nov 18, 2010 at 04:22:45PM +0000, Mel Gorman wrote: > > > Just to confirm - by hang, you mean grinds to a slow pace as opposed to > > > coming to a complete stop and having to restart? > > > > Hmm it's like if you're gigabytes in swap and apps hangs for a while > > and system is not really usable and it swaps for most new memory > > allocations despite there's plenty of memory free, but it's not a > > deadlock of course. > > > > Ok, but it's likely to be kswapd being very aggressive because it's > woken up frequently and tries to balance all zones. Once it's not > deadlocking entirely, there isn't a more fundamental bug hiding in there > somewhere. kswapd isn't activated by transhuge allocations because there's khugepaged for that and it's throttle to try a 2m alloc only once per minute if there's fragmentation. So the reason of the trashing is the direct lumpy. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 4EBF16B008A for ; Tue, 14 Dec 2010 11:07:50 -0500 (EST) Date: Tue, 14 Dec 2010 17:06:37 +0100 From: Andrea Arcangeli Subject: Re: [PATCH 55 of 66] select CONFIG_COMPACTION if TRANSPARENT_HUGEPAGE enabled Message-ID: <20101214160637.GB5638@random.random> References: <89a62752012298bb500c.1288798110@v2.random> <20101109151756.BC7B.A69D9226@jp.fujitsu.com> <20101109211145.GB6809@random.random> <20101118162245.GE8135@csn.ul.ie> <20101209190407.GJ19131@random.random> <20101214094556.GF13914@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101214094556.GF13914@csn.ul.ie> Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: KOSAKI Motohiro , linux-mm@kvack.org, Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, Marcelo Tosatti , Adam Litke , Avi Kivity , Hugh Dickins , Rik van Riel , Dave Hansen , Benjamin Herrenschmidt , Ingo Molnar , Mike Travis , KAMEZAWA Hiroyuki , Christoph Lameter , Chris Wright , bpicco@redhat.com, Balbir Singh , "Michael S. Tsirkin" , Peter Zijlstra , Johannes Weiner , Daisuke Nishimura , Chris Mason , Borislav Petkov List-ID: Hi Mel, On Tue, Dec 14, 2010 at 09:45:56AM +0000, Mel Gorman wrote: > On Thu, Dec 09, 2010 at 08:04:07PM +0100, Andrea Arcangeli wrote: > > On Thu, Nov 18, 2010 at 04:22:45PM +0000, Mel Gorman wrote: > > > Just to confirm - by hang, you mean grinds to a slow pace as opposed to > > > coming to a complete stop and having to restart? > > > > Hmm it's like if you're gigabytes in swap and apps hangs for a while > > and system is not really usable and it swaps for most new memory > > allocations despite there's plenty of memory free, but it's not a > > deadlock of course. > > > > Ok, but it's likely to be kswapd being very aggressive because it's > woken up frequently and tries to balance all zones. Once it's not > deadlocking entirely, there isn't a more fundamental bug hiding in there > somewhere. kswapd isn't activated by transhuge allocations because there's khugepaged for that and it's throttle to try a 2m alloc only once per minute if there's fragmentation. So the reason of the trashing is the direct lumpy. -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org