sched/fair: Trigger the update of blocked load on newly idle cpu

[ Upstream commit c6f88654 ]

Instead of waking up a random and already idle CPU, we can take advantage
of this_cpu being about to enter idle to run the ILB and update the
blocked load.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210224133007.28644-7-vincent.guittot@linaro.org


Stable-dep-of: ff47a0ac ("sched/fair: Check idle_cpu() before need_resched() to detect ilb CPU turning busy")
Signed-off-by: Sasha Levin <sashal@kernel.org>