From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763768AbXKNFjF (ORCPT ); Wed, 14 Nov 2007 00:39:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758813AbXKNFiw (ORCPT ); Wed, 14 Nov 2007 00:38:52 -0500 Received: from smtp109.mail.mud.yahoo.com ([209.191.85.219]:41287 "HELO smtp109.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1758738AbXKNFiu (ORCPT ); Wed, 14 Nov 2007 00:38:50 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:From:To:Subject:Date:User-Agent:Cc:References:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding:Content-Disposition:Message-Id; b=vReAqtJRNI5PPCYSXqmUBPWyi54JYf9BrN8MZH3Ui7Sk2N9r1z+59T9ftvVfHgSlQZ0QJExTXTjLO6BUIypP4Clcno/mXjm3xEp6njDmUXnCzW21sQjlifuH/E4YshHTnUH9nqVLvAGrpEwqV3KNi/AhEykvP8+YUoDVQ5WK1KM= ; X-YMail-OSG: wWrjJQQVM1l3gFTOqeVJmPHIGPDniP3E5wJoJqEBIgSZ9SfZJis.uEhRgma.MAS9B66YvPdcZw-- From: Nick Piggin To: David Miller Subject: Re: 2.6.24-rc2: Network commit causes SLUB performance regression with tbench Date: Wed, 14 Nov 2007 04:36:24 +1100 User-Agent: KMail/1.9.5 Cc: clameter@sgi.com, netdev@vger.kernel.org, herbert@gondor.apana.org.au, linux-kernel@vger.kernel.org References: <200711101229.35822.nickpiggin@yahoo.com.au> <200711132241.59074.nickpiggin@yahoo.com.au> <20071113.175804.151698768.davem@davemloft.net> In-Reply-To: <20071113.175804.151698768.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200711140436.24492.nickpiggin@yahoo.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 14 November 2007 12:58, David Miller wrote: > From: Nick Piggin > Date: Tue, 13 Nov 2007 22:41:58 +1100 > > > On Tuesday 13 November 2007 06:44, Christoph Lameter wrote: > > > On Sat, 10 Nov 2007, Nick Piggin wrote: > > > > BTW. your size-2048 kmalloc cache is order-1 in the default setup, > > > > wheras kmalloc(1024) or kmalloc(4096) will be order-0 allocations. > > > > And SLAB also uses order-0 for size-2048. It would be nice if SLUB > > > > did the same... > > > > > > You can try to see the effect that order 0 would have by booting with > > > > > > slub_max_order=0 > > > > Yeah, that didn't help much, but in general I think it would give > > more consistent and reliable behaviour from slub. > > Just a note that I'm not ignoring this issue, I just don't have time > to get to it yet. No problem. I would like to have helped more, but it's slow going given my lack of network stack knowledge. If I get any more interesting data, I'll send it. > I suspect the issue is about having a huge skb->data linear area for > TCP sends over loopback. We're likely getting a much smaller > skb->data linear data area after the patch in question, the rest using > the sk_buff scatterlist pages which are a little bit more expensive to > process. It didn't seem to be noticeable at 1 client. Unless scatterlist processing is going to cause cacheline bouncing, I don't see why this hurts more as you add CPUs?