Commit e85e6a21 authored Jan 10, 2019 by Paul E. McKenney

rcu: Unconditionally expedite during suspend/hibernate

The rcu_pm_notify() function refuses to switch to/from expedited grace
periods on systems with more than 256 CPUs due to the serialized
initialization of expedited grace periods. However, expedited grace
periods are now initialized in parallel, removing this concern.
This commit therefore removes the checks from rcu_pm_notify(), so that
expedited grace periods are used unconditionally during suspend/resume
and hibernate/wake operations.

As always, real-time workloads wishing to completely avoid expedited
grace periods can use the rcupdate.rcu_normal= kernel parameter.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

parent 9e98c678

kernel/rcu/tree.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -3559,12 +3559,10 @@ static int rcu_pm_notify(struct notifier_block *self,
		switch (action) {
		case PM_HIBERNATION_PREPARE:
		case PM_SUSPEND_PREPARE:
		if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */
		rcu_expedite_gp();
		break;
		case PM_POST_HIBERNATION:
		case PM_POST_SUSPEND:
		if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */
		rcu_unexpedite_gp();
		break;
		default:

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