[netperf-talk] Help me to understand the results

[Steevan Rodrigues]

Hi Rick,

Thanks for clarification.
How to change the method used to calculate CPU utilization ?
Do I need to configure netperf with flag enable-cpuutil=method ?
I am actually using this netperf on ARM board.
Which is the best method ?

Regards,
Steev


On Thu, Jan 27, 2011 at 11:36 PM, Rick Jones <rick.jones2 at hp.com> wrote:

> [discussions started in netperf-talk should remain there... ]
>
> Steevan Rodrigues wrote:
>
>> Hi Rick,
>>
>> Thanks for the explanation. That really helped us.
>>
>> I have one more question on CPU utilization reported by netperf.
>>
>> Does netperf report CPU utilization for the "netperf" tool or is it entire
>> CPU utilization accounting for other tasks that are running ?
>>
>> I am asking this question because I am seeing large difference between CPU
>> utilization reported by netperf and the "top" command.
>>
>> Could you please clarify this?
>>
>
> Sadly,
> http://www.netperf.org/svn/netperf2/trunk/doc/netperf.html#CPU-Utilizationdoes not address that directly.  I'll have to update it at some point.
>
> Netperf believes it is measuring the CPU utilization of the entire system
> and ass-u-me-s it is the only source of that CPU utilization.   That said,
> with the advent of HW threading and such, measuring "CPU utilization" has
> become rather more complicated and depending on the system, and the method
> netperf is using (see the URL above) I could see where there might be
> discrepancies.
>
> Based on the previous emails, and the netperf output contained therein, I
> would guess that the method being used by netperf is the /proc/stat method.
>  (The 'S' in the header portion for CPU utilization is the thing that makes
> me guess that).  There have been some "issues" in the past with format
> changes in /proc/stat that were not noticed by netperf.  You might compare
> the output of /proc/stat with the source code in src/netcpu_procstat.c
>  While doing-so, adding a -d to the global command line options to get the
> code to be a bit chatty about what it is doing might be goodness.
>
> happy benchmarking,
>
> rick jones
>
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