TOE performance
| From: |
| "David S. Miller" <davem-AT-davemloft.net> |
| To: |
| corbet-AT-lwn.net |
| Subject: |
| TOE performance |
| Date: |
| Wed, 31 Aug 2005 22:42:29 -0700 (PDT) |
| Cc: |
| jmorris-AT-namei.org, jgarzik-AT-pobox.com |
In response to: http://lwn.net/Articles/149941/
You might want to ask the Chelsio guys to provide some performance
metric other than their "land speed record" that, as Linux networking
stack maintainer, I'm frankly sick of hearing about over and over
again.
What's more interesting to me is an area I know TOE is poor in, and
that is TCP connection rates. It's all too easy to make one sole
connection pump a lot of data, but it's hard to make a web or database
server serve hundreds of thousands of connections per second. TOE
cards generally cannot do that because each connection setup/teardown
requires setting up and tearing down state on the network card, which
subsequently kills TCP connection rates.
So if you're a scientist trying to break the land speed record between
Stanford University in California and some place in the middle of
Europe on the other side of the planet, yeah TOE is probably a great
toy to play with.
TOE users are niche, always have been, and always will be. It is no
mistake that the Chelsio guys do not delve into this aspect of their
technology.
And the study they mentioned in their mail to you of course will be
full of accolades for their approach. If you read only the documents
posted on their web site, you might think that TOE is the best thing
since sliced bread.
The TOE folks are frankly between a rock and a hard place. They need
some support in upstream Linux for their solution to really be far
reaching and viable, yet the negative aspects of their technology are
such that this is likely not going to happen.
They also refuse to actively consider stateless offloads, which are
much better for long term maintainability and do not bypass the Linux
TCP networking stack we've been tuning for 10+ years. Doing so would
at least make these guys appear less anti-social and I would certainly
pay more attention to their concerns if they at least made some
efforts in this area. But they'll never do something so open minded
because their whole buisness model surrounds TOE.
With that in mind I applaud folks like Lenoid Grossman who are working
on stateless TCP receive offloads for highspeed networks on the
products they work on.
Take care.
Comments (2 posted)
Page editor: Jonathan Corbet
