[tip: core/rcu] rcu: Grace-period-kthread related sleeps to idle priority

[tip-bot2 for Paul E. McKenney]

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     77865dea25c4f45ce0c5bf61a8470af01fccd944
Gitweb:        https://git.kernel.org/tip/77865dea25c4f45ce0c5bf61a8470af01fccd944
Author:        Paul E. McKenney <paulmck@xxxxxxxxxx>
AuthorDate:    Thu, 07 May 2020 15:44:46 -07:00
Committer:     Paul E. McKenney <paulmck@xxxxxxxxxx>
CommitterDate: Mon, 29 Jun 2020 11:58:49 -07:00

rcu: Grace-period-kthread related sleeps to idle priority

This commit converts the long-standing schedule_timeout_interruptible()
and schedule_timeout_uninterruptible() calls used by RCU's grace-period
kthread to schedule_timeout_idle().  This conversion avoids polluting
the load-average with RCU-related sleeping.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/rcu/tree.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 874c831..feb31c2 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1638,7 +1638,7 @@ static void rcu_gp_slow(int delay)
 	if (delay > 0 &&
 	    !(rcu_seq_ctr(rcu_state.gp_seq) %
 	      (rcu_num_nodes * PER_RCU_NODE_PERIOD * delay)))
-		schedule_timeout_uninterruptible(delay);
+		schedule_timeout_idle(delay);
 }
 
 static unsigned long sleep_duration;
@@ -1661,7 +1661,7 @@ static void rcu_gp_torture_wait(void)
 	duration = xchg(&sleep_duration, 0UL);
 	if (duration > 0) {
 		pr_alert("%s: Waiting %lu jiffies\n", __func__, duration);
-		schedule_timeout_uninterruptible(duration);
+		schedule_timeout_idle(duration);
 		pr_alert("%s: Wait complete\n", __func__);
 	}
 }
@@ -2727,7 +2727,7 @@ static void rcu_cpu_kthread(unsigned int cpu)
 	}
 	*statusp = RCU_KTHREAD_YIELDING;
 	trace_rcu_utilization(TPS("Start CPU kthread@rcu_yield"));
-	schedule_timeout_interruptible(2);
+	schedule_timeout_idle(2);
 	trace_rcu_utilization(TPS("End CPU kthread@rcu_yield"));
 	*statusp = RCU_KTHREAD_WAITING;
 }