Commit bddf7122 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu-tasks: Restore use of timers for non-RT kernels 



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: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 777570d9

kernel/rcu/tasks.h

+7 −3
Original line number Diff line number Diff line
@@ -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);

		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++;