Re: RFE: More inclusive pid filtering of sched:sched_switch tracepoint events

[David Ahern <dsahern@gmail.com>]

On 11/18/15 12:01 PM, William Cohen wrote:
> Hi,
>
> I was experimenting with the sched:sched_switch tracepoint to look at
> the time that a process spend off the processor.  As a really simple
> experiment record data with:
>
> $ sudo perf record -e sched:sched_switch -- du
>
> Then examine the data with:
>
> $ sudo perf script
>
> The output only shows the sched:sched_switch when the process is moved
> off the processor.  However, there is no data showing when the process is
> scheduled back onto the processor:
>
>                du 20960 [007] 339893.429394: sched:sched_switch: du:20960 [120] R ==> kworker/7:0:16805 [120]
>                du 20960 [007] 339893.429411: sched:sched_switch: du:20960 [120] R ==> kworker/7:0:16805 [120]
>                du 20960 [007] 339893.429544: sched:sched_switch: du:20960 [120] R ==> kworker/7:0:16805 [120]
>                du 20960 [007] 339893.429556: sched:sched_switch: du:20960 [120] R ==> kworker/7:0:16805 [120]
>                du 20960 [007] 339893.429561: sched:sched_switch: du:20960 [120] R ==> kworker/7:0:16805 [120]
>                du 20960 [007] 339893.429567: sched:sched_switch: du:20960 [120] R ==> kworker/7:0:16805 [120]
>                du 20960 [007] 339893.430150: sched:sched_switch: du:20960 [120] R ==> kworker/7:0:16805 [120]
>
> Would it be possible to make perf's process filtering more inclusive so
> that output also includes sched:sched_switch tracepoints for pid that
> are also being scheduled onto the processor?  The alternative of
> recording all sched:sched_switch events system-wide and filtering out
> all the unwanted pid's is undesirable.

Known pain point. I thought Adrian had new sched tracepoints added to 
handle it, but I lost track of whether it was accepted.