Re: TCP Segmentation Offloading (TSO)

[Jeff Garzik <jgarzik@mandrakesoft.com>]

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