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

From: Paul E. McKenney
Date: Fri Dec 04 2015 - 18:58:15 EST


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(-)

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