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

[hbchen]

Talpey, Thomas wrote:

>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.
>
>  
>
Tom,
I am HB Chen from LANL not the Helen Chen from SNL.
I didn't run out of CPU.  It is about 70-80 % of CPU utilization.
 

>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 :-) )
>  
>
The IP over Myrinet ( Ethernet emulation) can reach upto 96%-98%  
bandwidth utilization why not the IPoIB ?

HB Chen
hbchen at lanl.gov

>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.  
>
>  
>

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