From mboxrd@z Thu Jan 1 00:00:00 1970 From: lm@bitmover.com (Larry McVoy) Subject: Re: tcp bw in 2.6 Date: Tue, 2 Oct 2007 14:26:08 -0700 Message-ID: <20071002212608.GG29944@bitmover.com> References: <20071002154137.GD17418@bitmover.com> <20071002164858.GH17418@bitmover.com> <20071002.141656.42880006.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: lm@bitmover.com, torvalds@linux-foundation.org, herbert@gondor.apana.org.au, wscott@bitmover.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from ipcop.bitmover.com ([192.132.92.15]:43957 "EHLO mail.bitmover.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753934AbXJBV0I (ORCPT ); Tue, 2 Oct 2007 17:26:08 -0400 Content-Disposition: inline In-Reply-To: <20071002.141656.42880006.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, Oct 02, 2007 at 02:16:56PM -0700, David Miller wrote: > We absolutely depend upon people like you to report when there are > anomalies like this. It's the only thing that scales. Well cool, finally doing something useful :) Is this issue no test setup? Because this does seem like something we'd want to have work well. > FWIW I have a t1000 Niagara box and an Ultra45 going through a netgear > gigabit switch. I'm getting 85MB/sec in one direction and 10MB/sec in > the other (using bw_tcp from lmbench3). Note that bw_tcp mucks with SND/RCVBUF. It probably shouldn't, it's been 12 years since that code went in there and I dunno if it is still needed. > Both are using identical > broadcom tigon3 gigabit chips and identical current kernels so that is > a truly strange result. > > I'll investigate, it may be the same thing you're seeing. Wow, sounds very similar. In my case I was seeing pretty close to 3x consistently. You're more like 8x, but I was all e1000 not broadcom. And note that sky2 doesn't have this problem. Does the broadcom do TSO? And sky2 not? I noticed a much higher CPU load for sky2. -- --- Larry McVoy lm at bitmover.com http://www.bitkeeper.com