[PATCH AUTOSEL 5.2 095/123] sched/psi: Reduce psimon FIFO priority

[Sasha Levin]

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

[ Upstream commit 14f5c7b46a41a595fc61db37f55721714729e59e ]

PSI defaults to a FIFO-99 thread, reduce this to FIFO-1.

FIFO-99 is the very highest priority available to SCHED_FIFO and
it not a suitable default; it would indicate the psi work is the
most important work on the machine.

Since Real-Time tasks will have pre-allocated memory and locked it in
place, Real-Time tasks do not care about PSI. All it needs is to be
above OTHER.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Tested-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 kernel/sched/psi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 7acc632c3b82b..7fe2c5fd26b54 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1051,7 +1051,7 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
 
 	if (!rcu_access_pointer(group->poll_kworker)) {
 		struct sched_param param = {
-			.sched_priority = MAX_RT_PRIO - 1,
+			.sched_priority = 1,
 		};
 		struct kthread_worker *kworker;
 
-- 
2.20.1