From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752805Ab0CBT35 (ORCPT ); Tue, 2 Mar 2010 14:29:57 -0500 Received: from cantor.suse.de ([195.135.220.2]:60333 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751694Ab0CBT34 (ORCPT ); Tue, 2 Mar 2010 14:29:56 -0500 Date: Tue, 2 Mar 2010 11:29:42 -0800 From: Greg KH To: Mel Gorman Cc: Alan Cox , KOSAKI Motohiro , Pekka Enberg , Christoph Lameter , Frans Pop , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: Memory management woes - order 1 allocation failures Message-ID: <20100302192942.GA2953@suse.de> References: <84144f021002260917q61f7c255rf994425f3a613819@mail.gmail.com> <20100301103546.DD86.A69D9226@jp.fujitsu.com> <20100302172606.GA11355@csn.ul.ie> <20100302183451.75d44f03@lxorguk.ukuu.org.uk> <20100302191110.GB11355@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100302191110.GB11355@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 On Tue, Mar 02, 2010 at 07:11:10PM +0000, Mel Gorman wrote: > On Tue, Mar 02, 2010 at 06:34:51PM +0000, Alan Cox wrote: > > > For reasons that are not particularly clear to me, tty_buffer_alloc() is > > > called far more frequently in 2.6.33 than in 2.6.24. I instrumented the > > > function to print out the size of the buffers allocated, booted under > > > qemu and would just "cat /bin/ls" to see what buffers were allocated. > > > 2.6.33 allocates loads, including high-order allocations. 2.6.24 > > > appeared to allocate once and keep silent. > > > > The pty layer is using them now and didn't before. That will massively > > distort your numhers. > > > > That makes perfect sense. It explains why only one allocation showed up > because it must belong to the tty attached to the serial console. > > Thanks Alan. > > > > While there have been snags recently with respect to high-order > > > allocation failures in recent kernels, this might be one of the cases > > > where it's due to subsystems requesting high-order allocations more. > > > > The pty code certainly triggered more such allocations. I've sent Greg > > patches to make the tty buffering layer allocate sensible sizes as it > > doesn't need multiple page allocations in the first place. > > > > Greg, what's the story with these patches? They are in -next and will go to Linus later on today for .34. thanks, greg k-h