[Beowulf] MPI performance gain with jumbo frames

[Bill Rankin]

Doug and Jeff have good points (and some good links).  On thing to  
also pay attention to is the CPU utilization during the bandwidth and  
application testing.  We found that on our cluster (various Dells  
with built in GigE NICs) while we did not see huge differences in  
effective bandwidth, the CPU overhead was notably less when using  
Jumbo Frames.

Again, YMMV.

Good luck,

-bill

On Jun 11, 2007, at 11:57 AM, Jeffrey B. Layton wrote:

> Doug brings up some good points. If you want to try Jumbo
> Frames to improve MPI performance you might have to
> tweak the TCP buffers as well. There are some links around
> the web on this. Sometimes it helps performance, sometimes
> it doesn't. Your mileage may vary.
>
> Jeff