From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: regression: unregister_netdev() unusably slow Date: Mon, 25 May 2009 00:47:39 +0200 Message-ID: <4A19CE8B.3070302@cosmosbay.com> References: <20090524192150.GE24757@kvack.org> <200905250023.31056.denys@visp.net.lb> <20090524213744.GG24757@kvack.org> <4A19BF39.4000305@cosmosbay.com> <20090524214433.GH24757@kvack.org> <4A19C50B.9040304@cosmosbay.com> <20090524221240.GI24757@kvack.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Denys Fedoryschenko , netdev@vger.kernel.org To: Benjamin LaHaise Return-path: Received: from gw1.cosmosbay.com ([212.99.114.194]:38014 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752524AbZEXWrx convert rfc822-to-8bit (ORCPT ); Sun, 24 May 2009 18:47:53 -0400 In-Reply-To: <20090524221240.GI24757@kvack.org> Sender: netdev-owner@vger.kernel.org List-ID: Benjamin LaHaise a =E9crit : > On Mon, May 25, 2009 at 12:07:07AM +0200, Eric Dumazet wrote: >> Maybe your HZ is too low ? Changing to 1000 HZ helps a lot >=20 > HZ is set to 1000. I turned off CONFIG_NO_HZ >=20 >> Also your hotplug config might do strange things at device removal ? >=20 > If it were CPU bound, maybe, but this behaviour is tied to the kernel= =20 > version in use. >=20 >> What distro do you use ? >=20 > It's an older Fedora 7 install inside kvm on a Fedora 10 host running= =20 > 2.6.30-rc7. >=20 OK thanks I switched HZ from 250 to 1000 and got : time ip link del vlan.899 real 0m0.011s user 0m0.000s sys 0m0.002s There is a strong dependancy against HZ BTW, I am using TREE_RCU # RCU Subsystem # CONFIG_CLASSIC_RCU is not set CONFIG_TREE_RCU=3Dy # CONFIG_PREEMPT_RCU is not set CONFIG_RCU_TRACE=3Dy CONFIG_RCU_FANOUT=3D32 # CONFIG_RCU_FANOUT_EXACT is not set CONFIG_TREE_RCU_TRACE=3Dy # CONFIG_PREEMPT_RCU_TRACE is not set # CONFIG_RCU_TORTURE_TEST is not set # CONFIG_RCU_CPU_STALL_DETECTOR is not set