[PATCH tip/core/rcu 0/10] Expedited-grace-period changes for 4.5

["Paul E. McKenney" <paulmck@linux.vnet.ibm.com>]

Hello!

This series contains follow-on cleanup changes to RCU's expedited
grace-period functionality.  The patches in this series are as follows:

1.	Short-circuit synchronize_sched_expedited() if there is only one CPU.

2.	Update comment to clarify the role of ->expmaskinitnext.

3.	Separate concerns by moving smp_mb() from rcu_seq_snap() to
	rcu_exp_gp_seq_snap().

4.	Safe a few lines of code by inverting the sense of
	sync_rcu_exp_select_cpus() "if" statement.

5.	Reduce expedited GP memory contention via per-CPU variables.

6.	Get rid of (some) empty stall-warning messages by resolving
	stall-warning ties.

7.	Add more diagnostics to expedited stall warning messages.

8.	Add rcu_normal kernel parameter to suppress expediting for
	the benefit of aggressive real-time systems.

9-10.	Allow expedited grace periods to be disabled just before init
	is spawned, allowing them to speed up boot without interfering
	with run-time real-time workloads.

							Thanx, Paul

------------------------------------------------------------------------

 b/Documentation/kernel-parameters.txt |   24 ++++++++--
 b/include/linux/rcupdate.h            |    6 ++
 b/init/main.c                         |    2 
 b/kernel/ksysfs.c                     |   22 ++++++++-
 b/kernel/rcu/srcu.c                   |    2 
 b/kernel/rcu/tree.c                   |   79 ++++++++++++++++++++++------------
 b/kernel/rcu/tree.h                   |   10 ++--
 b/kernel/rcu/tree_plugin.h            |    6 ++
 b/kernel/rcu/tree_trace.c             |   18 +++++--
 b/kernel/rcu/update.c                 |   17 +++++++
 10 files changed, 141 insertions(+), 45 deletions(-)