[openib-general] Re: cycles_to_units is incorrect in rdma_lat, rdma_bw.

[Shirley Ma]

> in case someone's firmware is less accurate than HP's.
> Shirley, did the patch to get_clock.c fix the problem?

Cycles is not equal to the clock rate. If you have a processor with 
internal doubling or pipelining or whatever, the clock rate isn't the 
same.

> Maybe there shall be a separate utility to compare
> get_cycles and gettimeofday results, may be useful for debug.
> 
> Anyway, if get_cpu_mhz isnt reliable people can just dump raw
> cycles data and do the math outside the tool.

Agree if the rdma_lat, and rdma_bw are only used for debugging/regression 
testing not for performance measurement.

Thanks
Shirley Ma
IBM Linux Technology Center
15300 SW Koll Parkway
Beaverton, OR 97006-6063
Phone(Fax): (503) 578-7638

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