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

[William Cohen <wcohen@redhat.com>]

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.

-Will