tree 0221b1c12b5c3e3ed7f2bb2ffc957b09891bcb51
parent 0989cb46783188ea7346ba6490be0046b9b7a725
author Paul E. McKenney <paul.mckenney@linaro.org> 1320242094 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1323628303 -0800

rcu: Allow dyntick-idle mode for CPUs with callbacks

Currently, RCU does not permit a CPU to enter dyntick-idle mode if that
CPU has any RCU callbacks queued.  This means that workloads for which
each CPU wakes up and does some RCU updates every few ticks will never
enter dyntick-idle mode.  This can result in significant unnecessary power
consumption, so this patch permits a given to enter dyntick-idle mode if
it has callbacks, but only if that same CPU has completed all current
work for the RCU core.  We determine use rcu_pending() to determine
whether a given CPU has completed all current work for the RCU core.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>