sched/fair: Fix sched_can_stop_tick() for fair tasks

[ Upstream commit c1f43c342e1f2e32f0620bf2e972e2a9ea0a1e60 ]

We can't stop the tick of a rq if there are at least 2 tasks enqueued in
the whole hierarchy and not only at the root cfs rq.

rq->cfs.nr_running tracks the number of sched_entity at one level
whereas rq->cfs.h_nr_running tracks all queued tasks in the
hierarchy.

Fixes: 11cc374f4643b ("sched_ext: Simplify scx_can_stop_tick() invocation in sched_can_stop_tick()")
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/20241202174606.4074512-2-vincent.guittot@linaro.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6cc12777bb11ab3d9395a1951daa0f85eb1451e3..d07dc87787dff37e2700a1cdf80578ceac225b41 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1300,7 +1300,7 @@ bool sched_can_stop_tick(struct rq *rq)
        if (scx_enabled() && !scx_can_stop_tick(rq))
                return false;
 
-       if (rq->cfs.nr_running > 1)
+       if (rq->cfs.h_nr_running > 1)
                return false;
 
        /*