Subject: Re: TSO on wm(4) (Intel Pro/1000): i82546 vs i8254EI vs others?
To: Jonathan Stone <>
From: Jason Thorpe <>
List: tech-net
Date: 05/20/2005 18:00:20
On May 20, 2005, at 3:56 PM, Jonathan Stone wrote:

> Without TSO, the 82544EI generates about 24,000 interrupts/sec at 123
> Mbyte/sec throughput, consuming about 50% CPU, with IPv4 and TCP
> checksum offload enabled.  When I also enable TSO on the 82544EI, I
> see about about 17,000 interrupts/sec and from 40% to 45% CPU load --
> not much of a delta from the pre-TSO number, and very close to twice
> the CPU cost of filling just one 82546 channel.

Intel actually de-supported TSO on the 82544 at one point.  There was  
an errata document on it.  They offered little specifics, simply  
claiming that it did not work to spec, and was thus no longer supported.

Try to find some 82545 single-port cards for your tests.

-- thorpej