[Beowulf] MPI performance gain with jumbo frames

[Paulo Afonso Lopes]

I can report a decrease of circa 10% CPU use per GbE link in an IBM x335
(dual Xeon 2.6GHz) with on-board Broadcom NICs and SMC switch, when going
from standard 1500 to 9K frames on the netperf benchmark, at full
bandwidth (circa 80MB/s).

Best Regards,

paulo

> 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
>
--
Paulo Afonso Lopes                        | Tel: +351- 21 294 8536
Departamento de Informática               | 294 8300 ext.10763
Faculdade de Ciências e Tecnologia        | Fax: +351- 21 294 8541
Universidade Nova de Lisboa               | e-mail: pal at di.fct.unl.pt
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