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Re: TOE brain dump

To: Werner Almesberger <werner@xxxxxxxxxxxxxxx>
Subject: Re: TOE brain dump
From: Nivedita Singhvi <niv@xxxxxxxxxx>
Date: Sat, 02 Aug 2003 10:32:55 -0700
Cc: netdev@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
In-reply-to: <20030802140444.E5798@almesberger.net>
References: <20030802140444.E5798@almesberger.net>
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Werner Almesberger wrote:

(*) The InfiniBand people unfortunately call also their TCP/IP
    bypass "TOE" (for which they promptly get shouted down,
    every time they use that word). This is misleading, because

Thank you! Yes! All in favor say Aye..AYE!!! Motion passes, the infiniband people don't get to call it TOE anymore..

While I'm not entirely convinced about the usefulness of TOE in
all the cases it's been suggested for, I can see value in certain
areas, e.g. when TCP per-packet overhead becomes an issue.

Ditto, but I see it being used to rollout the idea and process, rather than anything of value now, and the lessons are being learned for the future, when we reach 20Gb, 40Gb, even faster networks of tommorow. The processors might keep up, but nothing else will, for sure.

However, I consider the approach of putting a new or heavily
modified stack, which duplicates a considerable amount of the
functionality in the main kernel, on a separate piece of hardware
questionable at best. Some of the issues:

 - if this stack is closed source or generally hard to modify,
   security fixes will be slowed down

as will bug fixes, and debugging becomes a right royal pain.

Also, most profiles of networking applications show the
largest blip is essentially the user<->kernel transfer, and
that would still remain the unaddressed bottleneck.

So, how to do better ? Easy: use the Source, Luke. Here's my
idea:

 - instead of putting a different stack on the TOE, a
   general-purpose processor (probably with some enhancements,
   and certainly with optimized data paths) is added to the NIC

The thing is, all the TOE efforts are propietary ones, to my limited knowledge. Thus all the design is occurring in confidential, vendor internal forums. How will they/we come up with really the needed, _common_ design approach?

Or is this not so needed?

thanks,
Nivedita


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