Re: help in TCP checksum offload , TSO and zero copy

[Willy Tarreau <willy@w.ods.org>]

On Thu, Feb 26, 2004 at 10:52:19AM -0800, MP M wrote:
> ttcp-t: 216442880 bytes in 299.34 real seconds =
> 706.13 KB/sec +++
^^^^^^^^^

It's obvious that you have other problems, because lack of hardware
checksum won't lead to such abysmal performance. You should start
with *real* traffic, and not with I/O bound tools such as tar.
For instance, you'd better use "dd if=/dev/zero bs=64k count=4000"
(or use /dev/urandom) to generate some data if you absolutely need
some. But here, I'm fairly certain that your disk is *THE* problem.
I could easily reach the Gb/s with a P3/1G on a crappy dl2k, so I
don't see why you could not to it on better hardware.

Oh, and BTW, check your cable (netstat -i) to see if you get drops
or errors. You can also have poor wires which lead to frequent
retransmits. GigE uses all 4 pairs (8 wires), so a cable which
works well on FastEth is not necessarily OK on GigE.

Cheers,
Willy