Re: Early SPECWeb99 results on 2.5.33 with TSO on e1000

David S. Miller
2002-09-06T03:49:52Z

From: jamal <hadi@cyberus.ca>
Date: Thu, 5 Sep 2002 16:59:47 -0400 (EDT)

I would think shoving the data down the NIC
and avoid the fragmentation shouldnt give you that much significant
CPU savings.

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.

Ie. the headers that don't need to go across the bus are the critical
resource saved by TSO.

I think I've said this a million times, perhaps the next person who
tries to figure out where the gains come from can just reply with
a pointer to a URL of this email I'm typing right now :-)