From mboxrd@z Thu Jan 1 00:00:00 1970 From: Troy Wilson Subject: Re: Early SPECWeb99 results on 2.5.33 with TSO on e1000 Date: Fri, 6 Sep 2002 18:48:39 -0500 (CDT) Sender: linux-kernel-owner@vger.kernel.org Message-ID: <200209062348.g86NmdId016825@tempest.prismnet.com> References: <18563262.1031269721@[10.10.2.3]> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , hadi@cyberus.ca, linux-kernel@vger.kernel.org, netdev@oss.sgi.com, Nivedita Singhvi Return-path: In-Reply-To: <18563262.1031269721@[10.10.2.3]> "from Martin J. Bligh at Sep 5, 2002 11:48:42 pm" To: "Martin J. Bligh" List-Id: netdev.vger.kernel.org > > It's the DMA bandwidth saved, most of the specweb runs on x86 hardware > > is limited by the DMA throughput of the PCI host controller. In > > particular some controllers are limited to smaller DMA bursts to > > work around hardware bugs. > > I'm not sure that's entirely true in this case - the Netfinity > 8500R is slightly unusual in that it has 3 or 4 PCI buses, and > there's 4 - 8 gigabit ethernet cards in this beast spread around > different buses (Troy - are we still just using 4? My machine is not exactly an 8500r. It's an Intel pre-release engineering sample (8-way 900MHz PIII) box that is similar to an 8500r... there are some differences when going across the choerency filter (the bus that ties the two 4-way "halves" of the machine together). Bill Hartner has a test program that illustrates the differences-- but more on that later. I've got 4 PCI busses, two 33 MHz, and two 66MHz, all 64-bit. I'm configured as follows: PCI Bus 0 eth1 --- 3 clients 33 MHz eth2 --- Not in use PCI Bus 1 eth3 --- 2 clients 33 MHz eth4 --- Not in use PCI Bus 3 eth5 --- 6 clients 66 MHz eth6 --- Not in use PCI Bus 4 eth7 --- 6 clients 66 MHz eth8 --- Not in use > ... and what's > the raw bandwidth of data we're pushing? ... it's not huge). 2900 simultaneous connections, each at ~320 kbps translates to 928000 kbps, which is slightly less than the full bandwidth of a single e1000. We're spreading that over 4 adapters, and 4 busses. - Troy