From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 29 May 2001 02:45:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 29 May 2001 02:45:49 -0400 Received: from gateway.sequent.com ([192.148.1.10]:22965 "EHLO gateway.sequent.com") by vger.kernel.org with ESMTP id ; Tue, 29 May 2001 02:45:38 -0400 From: Nivedita Singhvi Message-Id: <200105290645.XAA29714@eng4.sequent.com> Subject: Re: Abysmal RECV network performance To: jw2357@hotmail.com Date: Mon, 28 May 2001 23:45:28 -0700 (PDT) Cc: linux-kernel@vger.kernel.org X-Mailer: ELM [version 2.5 PL3] 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 > Can someone please help me troubleshoot this problem - > I am getting abysmal (see numbers below) network performance > on my system, but the poor performance seems limited to receiving > data. Transmission is OK. [ snip ] > What kind of performance should I be seeing with a P-90 > on a 100Mbps connection? I was expecting something in the > range of 40-70 Mbps - certainly not 1-2 Mbps. > > What can I do to track this problem down? Has anyone else > had problems like this? While we didnt use 2.2 kernels at all, we did similar tests on 2.4.0 through 2.4.4 kernels, on UP and SMP. I've used a similar machine (PII 333MHz) as well as faster (866MHz) machines, and got pretty nifty (> 90Mbs) throughput on netperf tests (tcp stream, no disk I/O) over a 100Mb full duplex link. (not sure if there are any P-90 issues). Throughput does drop with small MTU, very small packet sizes, small socket buffer sizes, but only at extremes, for the most part throughput was well over 70Mbs. (this is true for single connections, you dont mention how many connections you were scaling to, if any). However, we did run into serious performance problems with the Netgear FA311/2 (tulip). Found that the link lost connectivity because of card lockups and transmit timeout failures - and some of these were silent. However, I moved to the 3C905C (3c59x driver) which behaved like a champ, and we didnt see the problems any more, so have stuck to that card. This was back in the 2.4.0 time frame, and there have many patches since then to various drivers, so not sure if the problem(s) have been resolved or not (likely to have been, extensively reported). Both your cards might actually be underperforming.. Are you seeing any errors reported in /var/log/messages? Are you monitoring your connection via tcpdump, for example? You might sometimes see long gaps in transmission...Are there any abnormal numbers in /proc/net/ stats? I dont remember seeing that high frame errors, although there were a few. HW checksumming for the kind of test you are doing (tcp, mostly fast path) will not buy you any real performance gain, the checksum is actually consumed by the user-kernel copy routine. You can also run the tests on a profiling kernel and compare results... Nivedita --- Nivedita Singhvi (503) 578-4580 Linux Technology Center nivedita@us.ibm.com IBM Beaverton, OR nivedita@sequent.com