Re: TCP Segmentation Offloading (TSO)

From: Jeff Garzik (jgarzik@mandrakesoft.com)
Date: Mon Sep 02 2002 - 14:06:39 EST


Feldman, Scott wrote:
> 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.

Are there docs or other drivers about?

8139C+ chip can do TSO, so I would like to implement support.

        Jeff

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