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Commit 5db35673 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Paul E. McKenney
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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: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarPaul 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);