sched/psi: Reduce psimon FIFO priority

[ 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@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 7acc632c3b82bebceeff2cfdc06eb652096f912b..7fe2c5fd26b54f42082727957c5066bab7207b3d 100644 (file)
--- 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;