Re: TOE brain dump

Werner Almesberger
2003-08-04T19:24:46Z

Eric W. Biederman wrote:
> The optimized for low latency cases seem to have a strong
> market in clusters.

Clusters have captive, no, _desperate_ customers ;-) And it
seems that people are just as happy putting MPI as their
transport on top of all those link-layer technologies.

> There is one place in low latency communications that I can think
> of where TCP/IP is not the proper solution. For low latency
> communication the checksum is at the wrong end of the packet.

That's one of the few things ATM's AAL5 got right. But in the end,
I think it doesn't really matter. At 1 Gbps, an MTU-sized packet
flies by within 13 us. At 10 Gbps, it's only 1.3 us. At that point,
you may well treat it as an atomic unit.

> On that score it is worth noting that the next generation of
> peripheral busses (Hypertransport, PCI Express, etc) are all switched.

And it's about time for that :-)

- Werner

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