Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932216AbbHYOd5 (ORCPT <rfc822;w@1wt.eu>);
	Tue, 25 Aug 2015 10:33:57 -0400
Received: from mail-pa0-f46.google.com ([209.85.220.46]:35146 "EHLO
	mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751564AbbHYOdz (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 25 Aug 2015 10:33:55 -0400
Message-ID: <1440513231.8932.14.camel@edumazet-glaptop2.roam.corp.google.com>
Subject: Re: [PATCH RFC 0/2] Optimize the snmp stat aggregation for large
 cpus
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: davem@davemloft.net, kuznet@ms2.inr.ac.ru, jmorris@namei.org,
        yoshfuji@linux-ipv6.org, kaber@trash.net, jiri@resnulli.us,
        edumazet@google.com, hannes@stressinduktion.org, tom@herbertland.com,
        azhou@nicira.com, ebiederm@xmission.com, ipm@chirality.org.uk,
        nicolas.dichtel@6wind.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, anton@au1.ibm.com,
        nacc@linux.vnet.ibm.com, srikar@linux.vnet.ibm.com
Date: Tue, 25 Aug 2015 07:33:51 -0700
In-Reply-To: <1440489266-31127-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com>
References: <y>
	 <1440489266-31127-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com>
Content-Type: text/plain; charset="UTF-8"
X-Mailer: Evolution 3.10.4-0ubuntu2 
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 850
Lines: 22

On Tue, 2015-08-25 at 13:24 +0530, Raghavendra K T wrote:
> While creating 1000 containers, perf is showing lot of time spent in
> snmp_fold_field on a large cpu system.
> 
> The current patch tries to improve by reordering the statistics gathering.
> 
> Please note that similar overhead was also reported while creating
> veth pairs  https://lkml.org/lkml/2013/3/19/556
> 
> Setup:
> 160 cpu (20 core) baremetal powerpc system with 1TB memory

I wonder if these kind of results would demonstrate cache coloring
problems on this host. Looks like all the per cpu data are colliding on
same cache lines.


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/