From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Hutchings Subject: Re: Network latency regressions from 2.6.22 to 2.6.29 Date: Thu, 16 Apr 2009 19:07:59 +0100 Message-ID: <1239905279.3203.30.camel@achroite> References: Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Christoph Lameter Return-path: Received: from smarthost01.mail.zen.net.uk ([212.23.3.140]:57170 "EHLO smarthost01.mail.zen.net.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753132AbZDPSIF (ORCPT ); Thu, 16 Apr 2009 14:08:05 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 2009-04-16 at 12:10 -0400, Christoph Lameter wrote: > The following are results of lantency measurements using udpping > (available from http://gentwo.org/ll). It shows that significant latencies > were added since 2.6.27. I surely wish we could get back to times below 90 > microseconds. [...] This "90 microseconds" figure is specific to a particular driver and hardware. Have you verified that it applies to others? The variation you've reported is tiny compared to the improvements that can be made or lost by hardware tuning. Ben. -- Ben Hutchings, Senior Software Engineer, Solarflare Communications Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.