From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 1 Aug 2019 10:41:31 +0000 (+0200)
Subject: sched/psi: Reduce psimon FIFO priority
X-Git-Tag: Ubuntu-5.10.0-12.13~4734^2~1
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=14f5c7b46a41a595fc61db37f55721714729e59e;p=mirror_ubuntu-hirsute-kernel.git

sched/psi: Reduce psimon FIFO priority

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>
---

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 7acc632c3b82..7fe2c5fd26b5 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;