From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760766AbXGXRxS (ORCPT ); Tue, 24 Jul 2007 13:53:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754919AbXGXRxL (ORCPT ); Tue, 24 Jul 2007 13:53:11 -0400 Received: from cantor.suse.de ([195.135.220.2]:46455 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752397AbXGXRxK (ORCPT ); Tue, 24 Jul 2007 13:53:10 -0400 To: Aaron Porter Cc: linux-kernel@vger.kernel.org Subject: Re: miserable performance of 2.6.21 under network load References: <20070724172513.GB24543@primate.net> From: Andi Kleen Date: 24 Jul 2007 20:48:00 +0200 In-Reply-To: <20070724172513.GB24543@primate.net> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Aaron Porter writes: > I'm in the process up upgrading a pool of apache servers from > 2.6.17.8 to 2.6.21.5, and we're seeing a pretty major change in behavior. > Under identical network load, 2.6.21 has a load average more than 3 times > higher, cpu 0 spends well over 90% of its time in interrupts (vs ~30% > under 2.6.17). When we hit 3k apache sessions, ksoftirqd eats 100% of cpu0 > and our network traffic drops off rapidly. The end result is that 2.6.17 > performs twice as well under this load. Can you oprofile it? -Andi