Re: Intel PEBS Load Latency Measurement

[Manuel Selva <selva.manuel@gmail.com>]

Thanks for this info. It confirms what I finally concluded after looking 
at source code where I saw that pid is used to get a task_struct object.

Manu

On 11/01/2013 09:41 AM, Namhyung Kim wrote:
> On Tue, 29 Oct 2013 14:20:09 +0100, Manuel Selva wrote:
>> One more thing I forgot to ask is clarification about the pid
>> parameter. According to Vince Weaver page: "If pid is 0, measurements
>> happen on the current thread, if pid is greater than 0, the process
>> indicated by pid is measured, and if pid is -1, all processes are
>> counted." and according to perf userland tool wiki page, it's possible
>> to attache to a specific thread with a -i option. As a consequence I
>> wonder how I can use the perf perf_event_sys_call to only count events
>> for a specific thread ?
>
> In the syscall's point of view, pid is actually tid AFAIK - so I works
> on the thread-basis not the process.
>
> Thanks,
> Namhyung
>