From owner-freebsd-hackers Mon Mar 19 6:25:57 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from list.framfab.se (list.framfab.se [195.54.96.202]) by hub.freebsd.org (Postfix) with ESMTP id ABD7F37B718 for ; Mon, 19 Mar 2001 06:25:54 -0800 (PST) (envelope-from Marten.Wikstrom@framfab.se) Received: from stoent001.framfab.se (mail.sto.framfab.se [172.16.200.241]) by list.framfab.se (8.9.3/8.9.3) with ESMTP id QAA02638 for ; Mon, 19 Mar 2001 16:19:18 +0100 Received: by STOENT001 with Internet Mail Service (5.5.2653.19) id ; Mon, 19 Mar 2001 15:23:00 +0100 Message-ID: From: =?iso-8859-1?Q?M=E5rten_Wikstr=F6m?= To: "'freebsd-hackers@freebsd.org'" Subject: Routing latency Date: Mon, 19 Mar 2001 15:22:56 +0100 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG I've performed a routing test between a FreeBSD box and a Linux box. I measured the latency and the result was not what I had expected. Both systems had the peak at 100 us (microseconds), but whereas the Linux = box had _no_ packet over 200 us, the FreeBSD box delayed some packets up to 2 = ms! Looking at the time series, it seems that the packets are delayed at = regular intervals, about every second. My guess is that some timer interrupt triggers every second and steals too much cpu. So my question is, how = can I decrease this routing delay? Test info: I used two identical boxes, each equipped with a Pentium Pro 200Mhz and = 64Mb mem. RedHat 7.0 with 2.4 kernel in one and FreeBSD 4.2-RELEASE in the = other. I used two DEC 100Mbit ethernet cards (21140 I think). I measured the latency with a SmartBits instrument. Fastforwarding was disabled. Three UDP streams was sent from the SmartBits to one of the ethernet cards in the box, which routed the streams to the other = interface, which in turn was connected back to the SmartBits. I had not made any changes to the standard kernel configuration. No = other processes was running in the background, apart from those necessary to perform the test. The ARP table was set statically, so no ARP traffic = would disturb. I would at least want to know what is causing the extra delays. /M=E5rten To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message