Re: [PerfSuite-users] CPU time greater than Wall clock time

[Rick K. <rk...@nc...>]

Naveen,

Thanks again for the update (and for raising this issue in the first 
place).  Just a couple of additional comments:

Naveen Parihar wrote:
> The second point involving the difference between Perfsuite CPU time 
> and Wall-clock time,  as you stated, can be explained by "time the 
> counters" or "count the timers". As you said, choosing one approach 
> depends on the objective. For my case, in either approach, the most 
> accurate measurements, will still have some overhead but I can imagine 
> scenarios, where changing from "count the timers" to "time the 
> counters"  might be helpful.
>

I appreciate your input on this and we will be updating the relevant 
library to make this change for the next major release.  Going forward, 
we will "time the counters" (or whatever is being measured), not the 
reverse.
 
> Please note that the numbers in this email are generated on a 
> full-blown voice recognition system. Earlier when I said "small test 
> program" I meant "small test example", sorry for the confusion that 
> this might have created. Unfortunately, due to license issues 
> involving the speech database, I can't share the experimental setup.

I understand.  We have been able to reproduce the behavior you reported 
with a small test case and are in the process of running a number of 
experiments to summarize the behavior under different conditions, using 
both the PerfSuite library as well as the PAPI high- and low-level 
APIs.  Results will be posted to this mailing list when complete.

Thanks once again for your feedback,

Rick