Commit 5db35673 authored Mar 30, 2010 by Lai Jiangshan Committed by Paul E. McKenney May 10, 2010

rcu: ignore offline CPUs in last non-dyntick-idle CPU check

Offline CPUs are not in nohz_cpu_mask, but can be ignored when checking
for the last non-dyntick-idle CPU. This patch therefore only checks
online CPUs for not being dyntick idle, allowing fast entry into
full-system dyntick-idle state even when there are some offline CPUs.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

parent 0c34029a

kernel/rcutree_plugin.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -1016,7 +1016,7 @@ int rcu_needs_cpu(int cpu)

		/* Don't bother unless we are the last non-dyntick-idle CPU. */
		for_each_cpu_not(thatcpu, nohz_cpu_mask)
		if (thatcpu != cpu) {
		if (cpu_online(thatcpu) && thatcpu != cpu) {
		per_cpu(rcu_dyntick_drain, cpu) = 0;
		per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
		return rcu_needs_cpu_quick_check(cpu);

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