From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264305AbTJOUai (ORCPT ); Wed, 15 Oct 2003 16:30:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264306AbTJOUah (ORCPT ); Wed, 15 Oct 2003 16:30:37 -0400 Received: from fledge.watson.org ([204.156.12.50]:18954 "EHLO fledge.watson.org") by vger.kernel.org with ESMTP id S264305AbTJOUad (ORCPT ); Wed, 15 Oct 2003 16:30:33 -0400 Date: Wed, 15 Oct 2003 16:27:35 -0400 (EDT) From: "Andrew R. Reiter" To: Chris Friesen cc: Davide Libenzi , Linux Kernel Subject: Re: question on incoming packets and scheduler In-Reply-To: <3F8DAA6B.7060609@nortelnetworks.com> Message-ID: <20031015162634.D56545@fledge.watson.org> References: <3F8CA55C.1080203@nortelnetworks.com> <3F8D8F3A.5040506@nortelnetworks.com> <3F8DAA6B.7060609@nortelnetworks.com> 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 On Wed, 15 Oct 2003, Chris Friesen wrote: :Davide Libenzi wrote: :> On Wed, 15 Oct 2003, Chris Friesen wrote: : :>>It appears that 2.4.20 fixes this issue, but there is another one :>>remaining that the latency appears to be dependent on the number of :>>incoming packets. See thread "incoming packet latency in 2.4.[18-20]" :>>for details. This behaviour doesn't show up in 2.6, and I'm about to :>>test 2.4.22. : :> Are you sure it's not a livelock issue during the burst? : :I dunno, you tell me. : :The test app simply sits in select() until a packet comes in, then it :spins on recvmsg() until there are no more messages. It uses :SO_TIMESTAMP to find out when the packet got to the kernel, and does a :gettimeofday() right after the recvmsg(), then calculates the delta for :each packet and the overall average. : :With 2.4.[18-20], the overall average goes up when the number of packets :goes up. For 2.6.0-test6, it stays constant. I would be interested in seeing the test be run with epoll too :) I ealize .18 doesn't support this, but how about it for .20? If not, perhaps you could shoot over the code and I could test? Cheers, Andrew -- Andrew R. Reiter arr@watson.org arr@FreeBSD.org