From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+w=401wt.eu-S1751818AbYJaPJB@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751818AbYJaPJB (ORCPT <rfc822;w@1wt.eu>);
	Fri, 31 Oct 2008 11:09:01 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751665AbYJaPIe
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Fri, 31 Oct 2008 11:08:34 -0400
Received: from rv-out-0506.google.com ([209.85.198.231]:54238 "EHLO
	rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751479AbYJaPId (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Fri, 31 Oct 2008 11:08:33 -0400
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version
         :content-type:content-transfer-encoding:content-disposition
         :references:x-google-sender-auth;
        b=lXZ4Tah6j1UvEaCUpIvi5zx8N1ZLkgImSWTce3wiG/OWb0p0vspLeVKP0C5wN4fGml
         kTxL7hpTZ2iYOHzNg6FDVdogXzp0IY0PMdMtuzGHeoCIB8FYuIHdRa0S2S7hM0SIUgkx
         MgFSfXivdRw3RnL2Um+bpDYcKpOx92r10qNbQ=
Message-ID: <84144f020810310808p9d6ecf9k6f10a671c21bf0da@mail.gmail.com>
Date: Fri, 31 Oct 2008 17:08:32 +0200
From: "Pekka Enberg" <penberg@cs.helsinki.fi>
To: "Evgeniy Polyakov" <s0mbre@tservice.net.ru>
Subject: Re: SLAB vs. SLUB tbench regression (Was: [tbench regression fixes]: digging out smelly deadmen.)
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
       "Peter Zijlstra" <a.p.zijlstra@chello.nl>,
       "Ingo Molnar" <mingo@elte.hu>, "David Miller" <davem@davemloft.net>,
       "Christoph Lameter" <cl@linux-foundation.org>,
       "Matthew Wilcox" <matthew@wil.cx>, "Eric Dumazet" <dada1@cosmosbay.com>,
       "Nick Piggin" <nickpiggin@yahoo.com.au>
In-Reply-To: <84144f020810310728j1f3b8a99se428ec55b0c165b5@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <84144f020810310728j1f3b8a99se428ec55b0c165b5@mail.gmail.com>
X-Google-Sender-Auth: 9f2a92acf6807af0
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Oct 31, 2008 at 4:28 PM, Pekka Enberg <penberg@cs.helsinki.fi> wrote:
> Hi Evgeniy,
>
> On Fri, Oct 10, 2008 at 1:17 AM, Evgeniy Polyakov
> <s0mbre@tservice.net.ru> wrote:
>> It was reported recently that tbench has a long history of regressions,
>> starting at least from 2.6.23 kernel. I verified that in my test
>> environment tbench 'lost' more than 100 MB/s from 470 down to 355
>> between at least 2.6.24 and 2.6.27. 2.6.26-2.6.27 performance regression
>> in my machines is rougly corresponds to 375 down to 355 MB/s.
>
> As you've already pointed out in private and in your blog, some part
> of the tbench regression comes from SLUB vs. SLAB as well. Looks like
> I can reproduce the regression locally as well:
>
>  [ 8 clients and tbench_srv on the same machine on 2-way x86-64 ]
>
>                  min      max      avg      sd
>  2.6.28-rc2-slab 234.57   244.88   242.68   0.71
>  2.6.28-rc2-slub 227.44   240.90   239.08   0.78

Christoph asked me to throw in the prefetch patch from Eric Dumazet.
Unfortunately, it doesn't seem to make much of a difference:

[ 2-way x86-64 with 8 clients and tbench_srv on the same machine ]

                           min      max      avg      sd
  2.6.28-rc2-slab          234.57   244.88   242.68   0.71
  2.6.28-rc2-slub          227.44   240.90   239.08   0.78
  2.6.28-rc2-slub+prefetch 237.42   244.32   239.78   0.92