For the tracing tool I have traced all interrupts, SoftIRQs, context switches, system calls and processes both from kernel and user space. And with Oprofile I have system-wide profiling data.
 My objective is to be able to interpret results from the tow tools: are they complementary so the comparison would not be correct (like idle time comparison) ?
Le Jeudi 17 avril 2014 22h54, Maynard Johnson <maynardj@us.ibm.com> a écrit :
On 04/17/2014 08:41 AM, Sabra Gargouri wrote:
> Hi,
> I 'm trying to compare results generated by Oprofile in one side and by a dynamic tracing tool based on Kprobes on other sides. I used both to test the same use case.
> Oprofile show 84% of idle time (poll_idle function) however only 63% with the tracing tool .
> Oprofile and the tracing tool don't give the same kind of results but I'm able to compute in percentage idle time for the tracing tool (by inspecting the process with pid 0).
> At the end I'am confusing why the results are different between the two tools.
You can't really use oprofile to try to determine the amount of idle time.  Once a process goes truly idle (say, waiting for synchronous I/O to complete), no cycles (or any other h/w events, for that matter) will be attributed to the idle process.

-Maynard

>
> Regards
>
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