Commit 8f5af6f1 authored May 04, 2012 by Paul E. McKenney Committed by Paul E. McKenney Jun 06, 2012

rcu: RCU_FAST_NO_HZ detection of callback adoption



In the present implementations of CPU hotplug, the outgoing CPU is
guaranteed to run its stop-machine process on the way out, which
will guarantee that RCU_FAST_NO_HZ forces the CPU out of dyntick-idle
mode.

However, new versions of CPU hotplug might not work this way.  This
commit therefore removes this design constraint by explicitly notifying
CPUs when they adopt non-lazy RCU callbacks.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Pascal Chapperon <pascal.chapperon@wanadoo.fr>

parent f8f5701b

kernel/rcutree.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1397,6 +1397,8 @@ static void rcu_adopt_orphan_cbs(struct rcu_state *rsp)
		rdp->qlen_lazy += rsp->qlen_lazy;
		rdp->qlen += rsp->qlen;
		rdp->n_cbs_adopted += rsp->qlen;
		if (rsp->qlen_lazy != rsp->qlen)
		rcu_idle_count_callbacks_posted();
		rsp->qlen_lazy = 0;
		rsp->qlen = 0;

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