From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263482AbTJOQQI (ORCPT ); Wed, 15 Oct 2003 12:16:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263477AbTJOQQI (ORCPT ); Wed, 15 Oct 2003 12:16:08 -0400 Received: from mail3.ithnet.com ([217.64.64.7]:22950 "HELO heather-ng.ithnet.com") by vger.kernel.org with SMTP id S263482AbTJOQQF (ORCPT ); Wed, 15 Oct 2003 12:16:05 -0400 X-Sender-Authentication: net64 Date: Wed, 15 Oct 2003 18:16:02 +0200 From: Stephan von Krawczynski To: Chris Friesen Cc: linux-kernel@vger.kernel.org Subject: Re: incoming packet latency in 2.4.[18-20] Message-Id: <20031015181602.07fd0959.skraw@ithnet.com> In-Reply-To: <3F8D6BB0.7060809@nortelnetworks.com> References: <3F8D6BB0.7060809@nortelnetworks.com> Organization: ith Kommunikationstechnik GmbH X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 15 Oct 2003 11:45:52 -0400 Chris Friesen wrote: > > There is an issue with incoming packet latency in the kernels mentioned. > > It seems that if you send in a burst of messages, the amount of time it > takes to wake the listening process is dependent on the size of the > message burst. 2.4.18-2.4.20 all show this behaviour, 2.6 doesn't. > > Some numbers for a udp message size of 2 bytes: > > 1 packet, average latency 12 usecs > 10 packets, average latency 66 usecs > 100 packets, average latency 477 usecs > > Is this a known issue? Is there an easy way to fix this, or is it > something inherent in the 2.4 architecture? Can you verify these numbers with 2.4.22 and 2.4.23-pre7 ? Regards, Stephan