From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754670Ab2GDPqA (ORCPT ); Wed, 4 Jul 2012 11:46:00 -0400 Received: from mail-ob0-f174.google.com ([209.85.214.174]:37886 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754366Ab2GDPp4 (ORCPT ); Wed, 4 Jul 2012 11:45:56 -0400 MIME-Version: 1.0 In-Reply-To: References: <1340389359-2407-1-git-send-email-js1304@gmail.com> <1340390729-2821-1-git-send-email-js1304@gmail.com> Date: Thu, 5 Jul 2012 00:45:56 +0900 Message-ID: Subject: Re: [PATCH 1/3 v2] slub: prefetch next freelist pointer in __slab_alloc() From: JoonSoo Kim To: Pekka Enberg Cc: Christoph Lameter , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Eric Dumazet , David Rientjes Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2012/7/5 Pekka Enberg : >> 2012/7/4 Pekka Enberg : >>> Well, can you show improvement in any benchmark or workload? >>> Prefetching is not always an obvious win and the reason we merged >>> Eric's patch was that he was able to show an improvement in hackbench. > > On Wed, Jul 4, 2012 at 5:30 PM, JoonSoo Kim wrote: >> I thinks that this patch is perfectly same effect as Eric's patch, so >> doesn't include benchmark result. >> Eric's patch which add "prefetch instruction" in fastpath works for >> second ~ last object of cpu slab. >> This patch which add "prefetch instrunction" in slowpath works for >> first object of cpu slab. > > Prefetching can also have negative effect on overall performance: > > http://lwn.net/Articles/444336/ > Thanks for good article which is very helpful to me. > That doesn't seem like that obvious win to me... Eric, Christoph? Could you tell me how I test this patch more deeply, plz? I am a kernel newbie and in the process of learning. I doesn't know what I can do more for this. I googling previous patch related to slub, some people use netperf. Just do below is sufficient? How is this test related to slub? for in in `seq 1 32` do netperf -H 192.168.0.8 -v 0 -l -100000 -t TCP_RR > /dev/null & done wait From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx133.postini.com [74.125.245.133]) by kanga.kvack.org (Postfix) with SMTP id 5FAA76B0070 for ; Wed, 4 Jul 2012 11:45:57 -0400 (EDT) Received: by ghrr18 with SMTP id r18so8144355ghr.14 for ; Wed, 04 Jul 2012 08:45:56 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1340389359-2407-1-git-send-email-js1304@gmail.com> <1340390729-2821-1-git-send-email-js1304@gmail.com> Date: Thu, 5 Jul 2012 00:45:56 +0900 Message-ID: Subject: Re: [PATCH 1/3 v2] slub: prefetch next freelist pointer in __slab_alloc() From: JoonSoo Kim Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: Christoph Lameter , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Eric Dumazet , David Rientjes 2012/7/5 Pekka Enberg : >> 2012/7/4 Pekka Enberg : >>> Well, can you show improvement in any benchmark or workload? >>> Prefetching is not always an obvious win and the reason we merged >>> Eric's patch was that he was able to show an improvement in hackbench. > > On Wed, Jul 4, 2012 at 5:30 PM, JoonSoo Kim wrote: >> I thinks that this patch is perfectly same effect as Eric's patch, so >> doesn't include benchmark result. >> Eric's patch which add "prefetch instruction" in fastpath works for >> second ~ last object of cpu slab. >> This patch which add "prefetch instrunction" in slowpath works for >> first object of cpu slab. > > Prefetching can also have negative effect on overall performance: > > http://lwn.net/Articles/444336/ > Thanks for good article which is very helpful to me. > That doesn't seem like that obvious win to me... Eric, Christoph? Could you tell me how I test this patch more deeply, plz? I am a kernel newbie and in the process of learning. I doesn't know what I can do more for this. I googling previous patch related to slub, some people use netperf. Just do below is sufficient? How is this test related to slub? for in in `seq 1 32` do netperf -H 192.168.0.8 -v 0 -l -100000 -t TCP_RR > /dev/null & done wait -- 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