Hi,

On 30/11/17 11:47, Patrick Bellasi wrote:

Currently schedutil updates are triggered for the RT class using a single
call place, which is part of the rt::update_curr_rt() used in:

- dequeue_task_rt:
  but it does not make sense to set the schedutil's SCHED_CPUFREQ_RT in
  case the next task should not be an RT one

- put_prev_task_rt:
  likewise, we set the SCHED_CPUFREQ_RT flag without knowing if required
  by the next task

- pick_next_task_rt:
  likewise, the schedutil's SCHED_CPUFREQ_RT is set in case the prev task
  was RT, while we don't yet know if the next will be RT

- task_tick_rt:
  that's the only really useful call, which can ramp up the frequency in
  case a RT task started its execution without a chance to order a
  frequency switch (e.g. because of the schedutil ratelimit)

Apart from the last call in task_tick_rt, the others are at least useless.
Thus, although being a simple solution, not all the call sites of that
update_curr_rt() are interesting to trigger a frequency switch as well as
some of the most interesting points are not covered by that call.
For example, a task set to RT has to wait the next tick to get the
frequency boost.

This patch fixes these issues by placing explicitly the schedutils
update calls in the only sensible places, which are:
- when an RT task wakes up and it's enqueued in a CPU
- when we actually pick a RT task for execution
- at each tick time
- when a task is set to be RT

Signed-off-by: Patrick Bellasi <redacted>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

Reviewed-by: Juri Lelli <juri.lelli@redhat.com>

Best,

Juri