[netperf-talk] Re: CPU calibration

[Rick Jones]

> I reconfigured Netperf with --enable-cpuutil=procstat and executed the
> same test. The results look slightly different but still a little off.
> To process 0.3 Mpbs of data it takes 2.9% CPU. The additional 0.4% in
> case of LOOPER might be because of the artifacts. 

Agreed - the use of LOOPER is not without overhead.

 > Using TOP I observed
> the CPU utilization of the Netserver process. It oscillates between
> 0.1% to 0.3%. Any ideas as to why this discrepancy?

Well, not all the CPU consumed on behalf of netperf will be charged to 
the netperf process.  That probably isn't all the difference though it 
might close the gap if you look at top's report of overall CPU util.

I suppose there is a possibility of math errors with such low CPU utils 
- there is IIRC some integer math happening there.  You might increase 
the traffic rate by one or two orders of magnitude and revisit the 
comparison.

netperf uses the stats exported via /proc/stat - I suppose that some 
manual calculations could also be done as a sanity check of netperf's math.

rick jones