On Mon, Feb 22, 2016 at 02:08:21PM -0300, Daniel Bristot de Oliveira wrote:

Deadline tasks behave differently of other tasks because deadline
task's also depend on their period, deadline and runtime.

Hence, the well known sched:sched_wakeup and sched:sched_switch
tracepoints are not always enough to precisely explain the behavior of a
deadline task with respect to the task's period, deadline, and runtime
consumption and replenishment.

In order to provide more precise information about the scheduling of
deadline tasks, this patch implements the following tracepoints:

- sched:sched_deadline_replenish: Informs the runtime replenishment of
a deadline task. Trace example:

  <idle>-0     [010] d.h.   268.428878: sched_deadline_replenish: \
	comm=y pid=1608 now=268.428876113 deadline=268.458863627  \
	runtime=20000000

The task y-1608 was replenished with 20000000 ns at 268.428876113
to be used until the deadline at 268.458863627.

- sched:sched_deadline_yield: Informs that a deadline task called
sched_yield(), and will wait for the next period. Trace example:

  y-1608  [010] d...   268.428892: sched_deadline_yield: 	\
	now=268.428891932 deadline=268.458863627		\
	remaining_runtime=19995653

The task y-1608 yielded before its deadline, with 19995653 ns of
remaining runtime.

- sched:sched_deadline_throttle: Informs that a task consumed all its
available runtime and was throttled. Trace example:

  t-1613  [011] d.h.   280.419823: sched_deadline_throttle:	\
	now=280.419823282 deadline=280.430683206 		\
	remaining_runtime=-13280

The task t-1613 overrun its runtime by 13280 ns and was throttled.

- sched:sched_deadline_block: Informs that a deadline task went to sleep
waiting to be awakened by another task. Trace example:

  b-1611  [011] d...   276.228298: sched_deadline_block: 	\
	now=276.228295889 deadline=276.258262555
	remaining_runtime=19966666

The task b-1611 blocked waiting for an external event. Its deadline is at
276.258262555, and it stills have 19966666 ns of remaining runtime on the
current period.

So I'm a bit allergic to tracepoints and this is very flimsy on reasons
why I would want to do this.

As it stands, the existing tracepoint have already been an ABI
trainwreck, why would I want to add more?