Re: More performance for the TCP stack by using additional hardware chip on NIC

[Kyle Moffett <mrmacman_g4@mac.com>]

On Apr 17, 2005, at 19:37, Horst von Brand wrote:
> Andreas Hartmann <andihartmann@01019freenet.de> said:
>> Alacritech developed a new chip for NIC's
>> (http://www.alacritech.com/html/tech_review.html), which makes it 
>> possible
>> to take away the TCP stack from the host CPU. Therefore, the host CPU 
>> has
>> more performance for the applications according Alacritech.
>>
>> This sounds interesting.
>
> This idea has been discussed around here a couple of times, and the
> consensus is that it is a bad idea: IP (and upper protocol) processing
> is not expensive, if done right, so this really doesn't buy much; this
> forces a particular interface to networking into the kernel, loosing
> flexibility that way is always bad; there is no access to futzing
> around in between (for example, for firewalling and such); and if the
> "hardware implementation" has bugs, you are screwed.

What I think would be _much_ more useful is a generic low-power 
multi-proc
MIPS/PPC system on a PCI card with a certain amount of RAM, etc that 
could
be programmed at runtime by the master CPU.  Then you lose none of the
flexibility, it can be run in the same endian-mode as the host CPU, and 
it
would allow you to program it for much more complicated DMA.  You could 
do
anything from linux software RAID, audio processing, encryption, TCP/IP
stack acceleration, extra scatter-gather for your disk controller, etc.
If it was low-cost, IE: cheaper than adding extra full-speed CPUs to the
system, and using a decent bi-endian, vector-capable CPU (Like PPC), you
might find that people will buy them for the flexibility.  Such a thing
might also be useful for the prezero folks, it could be used (when not
otherwise occupied) for zeroing unused pages.

Personally, I think I'd buy one or two just to tinker with them :-D.

Cheers,
Kyle Moffett

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