From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: Testing interface removal speedup patches from Eric Dumazet. Date: Mon, 09 May 2011 12:42:39 -0700 Message-ID: <4DC843AF.6050607@candelatech.com> References: <4DC83471.7030701@candelatech.com> <06627C760FB049F1A9321BC6@Ximines.local> <4DC83A57.40405@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev , Eric Dumazet To: Alex Bligh Return-path: Received: from mail.candelatech.com ([208.74.158.172]:58697 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754089Ab1EITmr (ORCPT ); Mon, 9 May 2011 15:42:47 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 05/09/2011 12:12 PM, Alex Bligh wrote: > > > --On 9 May 2011 12:02:47 -0700 Ben Greear wrote: > > >>> So Eric's patches help in the interface create case, even though >>> there is no synchronize_net, sychronize_sched() or rcu_barrier() there. >>> >>> I had assumed the slow create (which varies by number of pairs) was >>> down to sysfs scalability only (see difference between 14ms and 110ms >>> there). >> >> I'm not certain the create case is actually faster. Other runs on the >> patched kernel showed create to be much closer to the un-patched kernel. >> >> The ratios to create/delete are more consistent it seems. >> >>> Out of interest, if you still happen to have the scripts around, how >>> fast is veth creation if you just do 100 pairs? >> >> Created 500 veth in 17.874695 seconds (0.03574939 per interface). >> Created 100 veth in 2.779905 seconds (0.02779905 per interface). > > Hmmm... well you are getting *far* better linearity than me. Creating > 500 interfaces is 8 times slower *per interface* than doing 500. > > What occurs to me is that your box is faster than one of the ones I tested > on, and you use CONFIG_HZ=100 but you get poorer results in absolute terms > doing 100 (I see 14ms per interface). This with everything listenting to > udev disabled? (so udevd dead, whatever executes your ifup/down scripts > dead, unshare -n). I use HZ of 1000, btw. I killed udev, haldaemon..seemed to be just my stuff running. I don't see any 'ifup' running with these things dead... If you want to post your script, I can run it on my machine... Thanks, Ben > -- Ben Greear Candela Technologies Inc http://www.candelatech.com