[openib-general] ip over ib throughtput

[Grant Grundler]

On Thu, Jan 06, 2005 at 01:44:39AM -0700, Stephen Poole wrote:
> Remember, even Ethernet finally decided to go to Jumbo 
> Frames, why, system impact and more.

I think jumbo frames was proposed because it was easier to implement
than TCP segmentation offloading. The result is effectively the same
by reducing the per message overhead.

Jumbo frames also required the switches support 9K frames and
my understanding is few do.

And having a 2G upper limit on the message size seems far in excess
of where system load would matter. Today, with mass storage, the
"sweet spot" in transfer size is ~256KB. I.e. bigger sizes don't
measurable reduce the system overhead. I expect IB to see similar
results - possibly with even smaller message sizes.

grant