Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754266AbaFKS1P (ORCPT ); Wed, 11 Jun 2014 14:27:15 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:41858 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752436AbaFKS1O (ORCPT ); Wed, 11 Jun 2014 14:27:14 -0400 Message-ID: <53989F7B.6000004@canonical.com> Date: Wed, 11 Jun 2014 13:27:07 -0500 From: Dave Chiluk Reply-To: chiluk@canonical.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: Rafael Tinoco , linux-kernel@vger.kernel.org, davem@davemloft.net, ebiederm@xmission.com, Christopher Arges , Jay Vosburgh Subject: Re: Possible netns creation and execution performance/scalability regression since v3.8 due to rcu callbacks being offloaded to multiple cpus References: <20140611133919.GZ4581@linux.vnet.ibm.com> <539879B8.4010204@canonical.com> <20140611161857.GC4581@linux.vnet.ibm.com> In-Reply-To: <20140611161857.GC4581@linux.vnet.ibm.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/11/2014 11:18 AM, Paul E. McKenney wrote: > On Wed, Jun 11, 2014 at 10:46:00AM -0500, David Chiluk wrote: >> Now think about what happens when a gateway goes down, the namespaces >> need to be migrated, or a new machine needs to be brought up to replace >> it. When we're talking about 3000 namespaces, the amount of time it >> takes simply to recreate the namespaces becomes very significant. >> >> The script is a stripped down example of what exactly is being done on >> the neutron gateway in order to create namespaces. > > Are the namespaces torn down and recreated one at a time, or is there some > syscall, ioctl(), or whatever that allows bulk tear down and recreating? > > Thanx, Paul In the normal running case, the namespaces are created one at a time, as new customers create a new set of VMs on the cloud. However, in the case of failover to a new neutron gateway the namespaces are created all at once using the ip command (more or less serially). As far as I know there is no syscall or ioctl that allows bulk tear down and recreation. if such a beast exists that might be helpful. -- 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/