[openib-general] Question about the IPoIB bandwidth performance ?

[Talpey, Thomas]

At 11:38 AM 6/5/2006, hbchen wrote:
>Even with this IB-4X = 8Gb/sec = 1024 MB/sec the IPoIB bandwidth utilization is still very low.
>>> IPoIB=420MB/sec  
>>> bandwidth utilization= 420/1024 = 41.01%


Helen, have you measured the CPU utilizations during these runs?
Perhaps you are out of CPU.

Outrageous opinion follows.

Frankly, an IB HCA running Ethernet emulation is approximately the
world's worst 10GbE adapter (not to put too fine of a point on it :-) )
There is no hardware checksumming, nor large-send offloading, both
of which force overhead onto software. And, as you just discovered
it isn't even 10Gb!

In general, network emulation layers are always going to perform more
poorly than native implementations. But this is only a generality learned
from years of experience with them.

Tom.