One question regarding the throughput numbers, what was the size of the packets built at the tcp layer (mss)? i assume the mtu is ethernet 1500 Bytes, right? and that mss should be something much bigger than mtu, which gives the performance improvement shown in the numbers. thanks, jordi -----Original Message----- From: linux-net-owner@vger.kernel.org [mailto:linux-net-owner@vger.kernel.org]On Behalf Of Feldman, Scott Sent: Monday, September 02, 2002 10:45 AM To: linux-kernel@vger.kernel.org; linux-net; 'Dave Hansen'; 'Manand@us.ibm.com' Cc: kuznet@ms2.inr.ac.ru; 'David S. Miller'; Leech, Christopher Subject: TCP Segmentation Offloading (TSO) TCP Segmentation Offloading (TSO) is enabled[1] in 2.5.33, along with an enabled e1000 driver. Other capable devices can be enabled ala e1000; the driver interface (NETIF_F_TSO) is very simple. So, fire up you favorite networking performance tool and compare the performance gains between 2.5.32 and 2.5.33 using e1000. I ran a quick test on a dual P4 workstation system using the commercial tool Chariot: Tx/Rx TCP file send long (bi-directional Rx/Tx) w/o TSO: 1500Mbps, 82% CPU w/ TSO: 1633Mbps, 75% CPU Tx TCP file send long (Tx only) w/o TSO: 940Mbps, 40% CPU w/ TSO: 940Mbps, 19% CPU A good bump in throughput for the bi-directional test. The Tx-only test was already at wire speed, so the gains are pure CPU savings. I'd like to see SPECWeb results w/ and w/o TSO, and any other relevant testing. UDP framentation is not offloaded, so keep testing to TCP. -scott [1] Kudos to Alexey Kuznetsov for enabling the stack with TSO support, to Chris Leech for providing the e1000 bits and a prototype stack, and to David Miller for consultation. - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
