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

[Grant Grundler]

On Thu, Jun 09, 2005 at 08:52:10PM -0700, Shirley Ma wrote:
> > Does rdma_lat have the same issue?
> > What does rdma_lat report?
> 
> Latency typical: 0.717812 usec
> Latency best   : 0.705625 usec
> 
> Latency typical: 1149 cycles
> Latency best   : 1129.5 cycles
> 

I'm convinced something is broken and that gettimeofday()
works better in your case.

Please provide "cat /proc/cpuinfo" output so I can rule out
broken firmware and look for something else.

> after modifying the per usec cycles 
> the results are:
> 
> Latency typical: 5.76884 usec
> Latency best   : 5.66834 usec
> 
> gettimeofday() results are:
> 
> Latency typical: 6.000000 usec
> Latency best   : 5.500000 usec

These result suggest gettimeofday() is not very accurate
and less reliable.

Note that I currently have patches outstanding on both
rdma_bw.c and rdma_lat.c. I'm waiting for Michael to
reject, accept, or comment on them. Or can someone else
commit changes to those files for me?

thanks,
grant