From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Bligh Subject: Re: Scalability of interface creation and deletion Date: Sun, 08 May 2011 09:06:11 +0100 Message-ID: <8E10C0B83130C288FD7BA9B8@nimrod.local> References: <891B02256A0667292521A4BF@Ximines.local> <1304770926.2821.1157.camel@edumazet-laptop> <0F4A638C2A523577CDBC295E@Ximines.local> <1304785589.3207.5.camel@edumazet-laptop> <178E8895FB84C07251538EF7@Ximines.local> <1304793174.3207.22.camel@edumazet-laptop> <1304793749.3207.26.camel@edumazet-laptop> <1304838742.3207.45.camel@edumazet-laptop> Reply-To: Alex Bligh Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, "Paul E. McKenney" , Alex Bligh To: Eric Dumazet Return-path: Received: from mail.avalus.com ([89.16.176.221]:57108 "EHLO mail.avalus.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751502Ab1EHIGO (ORCPT ); Sun, 8 May 2011 04:06:14 -0400 In-Reply-To: <1304838742.3207.45.camel@edumazet-laptop> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: Eric, > By the way, if I change HZ from 1000 to 100 I now have ten times slower > result : > ># ip link add link eth0 eth0.103 type vlan id 103 ># time ip link del eth0.103 > > real 0m0.430s > user 0m0.000s > sys 0m0.000s > > So all this is related to your HZ value, even in a CONFIG_NO_HZ=y > kernel. That's very mysterious. > Alex, I guess you have HZ=250 ? I have HZ=100. I am basically using the Ubuntu default with localmodconfig to make compile times sensible. amb@nattytest:~$ cd kernel/linux-2.6/ amb@nattytest:~/kernel/linux-2.6$ fgrep HZ .config CONFIG_RCU_FAST_NO_HZ=y CONFIG_NO_HZ=y CONFIG_HZ_100=y # CONFIG_HZ_250 is not set # CONFIG_HZ_300 is not set # CONFIG_HZ_1000 is not set CONFIG_HZ=100 # CONFIG_MACHZ_WDT is not set -- Alex Bligh