ANDROID: sched/rt: schedtune: Add boost retention to RT

Boosted RT tasks can be deboosted quickly, this makes boost usless
for RT tasks and causes lots of glitching. Use timers to prevent
de-boost too soon and wait for long enough such that next enqueue
happens after a threshold.

While this can be solved in the governor, there are following
advantages:
- The approach used is governor-independent
- Reduces boost group lock contention for frequently sleepers/wakers

Note:
Fixed build breakage due to schedfreq dependency which isn't used
for RT anymore.

Bug: 30210506

Change-Id: I428a2695cac06cc3458cdde0dea72315e4e66c00
Signed-off-by: Joel Fernandes <joelaf@google.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4645017c6a24..d3dd0d516957 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1434,6 +1434,10 @@ struct sched_rt_entity {
 	unsigned long watchdog_stamp;
 	unsigned int time_slice;
 
+	/* Accesses for these must be guarded by rq->lock of the task's rq */
+	bool schedtune_enqueued;
+	struct hrtimer schedtune_timer;
+
 	struct sched_rt_entity *back;
 #ifdef CONFIG_RT_GROUP_SCHED
 	struct sched_rt_entity	*parent;