From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id DB62E6B0047 for ; Tue, 2 Mar 2010 14:11:31 -0500 (EST) Date: Tue, 2 Mar 2010 19:11:10 +0000 From: Mel Gorman Subject: Re: Memory management woes - order 1 allocation failures Message-ID: <20100302191110.GB11355@csn.ul.ie> References: <84144f021002260917q61f7c255rf994425f3a613819@mail.gmail.com> <20100301103546.DD86.A69D9226@jp.fujitsu.com> <20100302172606.GA11355@csn.ul.ie> <20100302183451.75d44f03@lxorguk.ukuu.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20100302183451.75d44f03@lxorguk.ukuu.org.uk> Sender: owner-linux-mm@kvack.org To: Alan Cox Cc: KOSAKI Motohiro , Pekka Enberg , Greg Kroah-Hartman , Christoph Lameter , Frans Pop , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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