From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Dichtel Subject: Re: [iproute PATCH 0/2] Netns performance improvements Date: Fri, 8 Jul 2016 10:01:13 +0200 Message-ID: <577F5DC9.7020303@6wind.com> References: <1467729773-16751-1-git-send-email-phil@nwl.cc> <87twg4ywjz.fsf@x220.int.ebiederm.org> <20160705205103.GE620@orbyte.nwl.cc> <87h9c259ip.fsf@x220.int.ebiederm.org> <20160707111718.GL620@orbyte.nwl.cc> <577E5244.8030601@6wind.com> <20160707154809.GN620@orbyte.nwl.cc> <577E8054.6040603@hpe.com> Reply-To: nicolas.dichtel@6wind.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE To: Rick Jones , Phil Sutter , "Eric W. Biederman" , Stephen Hemminger , netdev@vger.kernel.org Return-path: Received: from mail-wm0-f45.google.com ([74.125.82.45]:37562 "EHLO mail-wm0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750714AbcGHIBQ (ORCPT ); Fri, 8 Jul 2016 04:01:16 -0400 Received: by mail-wm0-f45.google.com with SMTP id k123so7592764wme.0 for ; Fri, 08 Jul 2016 01:01:15 -0700 (PDT) In-Reply-To: <577E8054.6040603@hpe.com> Sender: netdev-owner@vger.kernel.org List-ID: Le 07/07/2016 18:16, Rick Jones a =C3=A9crit : > On 07/07/2016 08:48 AM, Phil Sutter wrote: >> On Thu, Jul 07, 2016 at 02:59:48PM +0200, Nicolas Dichtel wrote: >>> Le 07/07/2016 13:17, Phil Sutter a =C3=A9crit : >>> [snip] >>>> The issue came up during OpenStack Neutron testing, see this ticke= t for >>>> reference: >>>> >>>> https://bugzilla.redhat.com/show_bug.cgi?id=3D1310795 >>> Access to this ticket is not public :( >> >> *Sigh* OK, here are a few quotes: >> >> "OpenStack Neutron controller nodes, when undergoing testing, are >> locking up specifically during creation and mounting of namespaces. >> They appear to be blocking behind vfsmount_lock, and contention for = the >> namespace_sem" >> >> "During the scale testing, we have 300 routers, 600 dhcp namespaces >> spread across four neutron network nodes. When then start as one set= of >> standard Openstack Rally benchmark test cycle against neutron. An >> example scenario is creating 10x networks, list them, delete them an= d >> repeat 10x times. The second set performs an L3 benchmark test betwe= en >> two instances." >> >=20 > Those 300 routers will each have at least one namespace along with th= e dhcp > namespaces. Depending on the nature of the routers (Distributed vers= us > Centralized Virtual Routers - DVR vs CVR) and whether the routers are= supposed > to be "HA" there can be more than one namespace for a given router. >=20 > 300 routers is far from the upper limit/goal. Back in HP Public Clou= d, we were > running as many as 700 routers per network node (*), and more than fo= ur network > nodes. (back then it was just the one namespace per router and networ= k). Mileage > will of course vary based on the "oomph" of one's network node(s). Thank you for the details. Do you have a script or something else to easily reproduce this problem= ?