sched/fair: Add new cfs_rq.h_nr_runnable

[ Upstream commit c2a295bf ]

With delayed dequeued feature, a sleeping sched_entity remains queued in
the rq until its lag has elapsed. As a result, it stays also visible
in the statistics that are used to balance the system and in particular
the field cfs.h_nr_queued when the sched_entity is associated to a task.

Create a new h_nr_runnable that tracks only queued and runnable tasks.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20241202174606.4074512-5-vincent.guittot@linaro.org


Stable-dep-of: aa3ee4f0 ("sched/fair: Fixup wake_up_sync() vs DELAYED_DEQUEUE")
Signed-off-by: Sasha Levin <sashal@kernel.org>