Ah, okay, it had occurred to me that might be the case, but I don't
have root on that machine so I couldn't test it before asking on the
list.  Is there a way to uniquely measure a multithreaded application
that doesn't require root?  I tried just using something like task or
task_smpl, but on a pthread application with two threads it only
appears to monitor the main thread and not the worker child (based on
a comparison of instruction count from task and from Pin).

-dan

On Fri, Jul 15, 2011 at 5:03 PM, Vince Weaver <vweav...@eecs.utk.edu> wrote:
> On Fri, 15 Jul 2011, Dan Upton wrote:
>
>> I'm trying to monitor some multithreaded applications and I just found
>> the task_cpu example tool.  I can't get it to attach to any program
>> though, single or multithreaded, even something as simple as ls:
>>
>> $ ./task_cpu -- /bin/ls
>> task_cpu: cannot attach event0 PERF_COUNT_HW_CPU_CYCLES: Permission denied
>>
>> However, task_smpl and task work fine.  Is something special required
>> to get task_cpu to work?
>
> For security reasons you need root permission to access the CPU-level
> counters.  This is because when you monitor CPU-wide you monitor *all*
> processes on the CPU, including ones that don't belong to you.
>
> Vince
>

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