The use of hrtimers for RCU-tasks grace-period delays works well in
general, but can result in excessive grace-period delays for some
corner-case workloads. This commit therefore reverts to the use of
timers for non-RT kernels to mitigate those grace-period delays.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/tasks.h | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 71fe340ab82a..405614039515 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -654,9 +654,13 @@ static void rcu_tasks_wait_gp(struct rcu_tasks *rtp)
// Slowly back off waiting for holdouts
set_tasks_gp_state(rtp, RTGS_WAIT_SCAN_HOLDOUTS);
- exp = jiffies_to_nsecs(fract);
- __set_current_state(TASK_IDLE);
- schedule_hrtimeout_range(&exp, jiffies_to_nsecs(HZ / 2), HRTIMER_MODE_REL_HARD);
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ schedule_timeout_idle(fract);
+ } else {
+ exp = jiffies_to_nsecs(fract);
+ __set_current_state(TASK_IDLE);
+ schedule_hrtimeout_range(&exp, jiffies_to_nsecs(HZ / 2), HRTIMER_MODE_REL_HARD);
+ }
if (fract < HZ)
fract++;
--
2.31.1.189.g2e36527f23
