From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Performance degradation on 2.6.25 kernels for http servers Date: Wed, 23 Jul 2008 13:37:30 -0700 Message-ID: <4887968A.10308@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: NetDev Return-path: Received: from mail.candelatech.com ([208.74.158.172]:59146 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754402AbYGWUhc (ORCPT ); Wed, 23 Jul 2008 16:37:32 -0400 Received: from [192.168.100.194] (static-71-121-249-218.sttlwa.dsl-w.verizon.net [71.121.249.218]) (authenticated bits=0) by ns3.lanforge.com (8.14.2/8.14.2) with ESMTP id m6NKbU57029016 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 23 Jul 2008 13:37:31 -0700 Sender: netdev-owner@vger.kernel.org List-ID: We noticed something strange today. We have a test that launches 10 http clients that request a small URL over and over again. Keep-alive is enabled on clients and apache. When using a 2.6.24 or earlier kernel on the web server, we get around 1200 urls per second completed on each of the 10 clients. With 2.6.25 kernel we get around 1000 urls per second completed. In other words, about a 20% degradation in connections per second. We see the same affect when we use standard Fedora kernels as when we use our own patched kernels. We see similar degradations when using FC5 and FC8, and 32-bit and 64-bit installs. We see similar degradations on different hardware systems. We have only tried our modified kernels and standard Fedora kernels at this time (no un-modified kernels from kernel.org). It could still be something we are doing wrong, but if anyone else has a similar test case, I'm curious to know if you see similar degradations. Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com