rcu: Avoid IPIing idle CPUs from synchronize_sched_expedited()
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Wed, 3 Sep 2014 19:25:56 +0000 (12:25 -0700)
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Tue, 28 Oct 2014 20:49:30 +0000 (13:49 -0700)
commite0775cefb5ede661dbdc0611d7bf3fcd4640005c
tree58bf71c00bef3462c92649ef80b393c44dd412f5
parent61cfd0970ea27764434fba5c41bdaefb26c44183
rcu: Avoid IPIing idle CPUs from synchronize_sched_expedited()

Currently, synchronize_sched_expedited() sends IPIs to all online CPUs,
even those that are idle or executing in nohz_full= userspace.  Because
idle CPUs and nohz_full= userspace CPUs are in extended quiescent states,
there is no need to IPI them in the first place.  This commit therefore
avoids IPIing CPUs that are already in extended quiescent states.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
kernel/rcu/tree.c