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Subject[PATCH tip/core/rcu 0/23] Improvements to RT response on big systems and expedited functions
Hello!

This patch series contains additional improvements to latency for
large systems (beyond those in 3.6), along with improvements to
synchronize_rcu_expedited(). It also fixes one race introduced by the
latency improvements and another that was there to start with (but made
more probable by the latency improvements). These are in a single
series due to conflicts that would otherwise occur. The individual
patches are as follows:

1-6. Move RCU grace-period initialization and cleanup into a kthread:
1. Move RCU grace-period initialization into kthread.
2. Allow RCU grace-period initialization to be preempted.
3. Move RCU grace-period cleanup into kthread.
4. Allow RCU grace-period cleanup to be preempted.
5. Prevent offline CPUs from executing RCU core code.
6. Break up rcu_gp_kthread() into subfunctions.
7. Provide an OOM handler to allow lazy callbacks to be motivated
under memory pressure.
8. Segregate rcu_state fields to improve cache locality
(Courtesy of Dimitri Sivanich).
9-12. Move RCU grace-period forcing into a kthread.
9. Move quiescent-state forcing into kthread.
10. Allow RCU quiescent-state forcing to be preempted.
11. Adjust debugfs tracing for kthread-based quiescent-state
forcing.
12. Prevent force_quiescent_state() memory contention.
13. Control grace-period duration from sysfs.
14. Remove now-unused rcu_state fields.
15. Make rcutree module parameters visible in sysfs.
16. Prevent initialization-time quiescent-state race.
17. Fix day-zero grace-period initialization/cleanup race.
18. Add random PROVE_RCU_DELAY to provoke initalization races.
19. Adjust for unconditional ->completed assignment.
20. Remove callback acceleration from grace-period initialization
due it no longer being safe.
21. Eliminate signed overflow in synchronize_rcu_expedited().
22. Reduce synchronize_rcu_expedited() latency.
23. Simplify quiescent-state detection.

Thanx, Paul

------------------------------------------------------------------------
b/Documentation/RCU/trace.txt | 43 -
b/Documentation/kernel-parameters.txt | 11
b/kernel/rcutree.c | 191 +++++---
b/kernel/rcutree.h | 3
b/kernel/rcutree_plugin.h | 80 +++
b/kernel/rcutree_trace.c | 3
kernel/rcutree.c | 805 +++++++++++++++++-----------------
kernel/rcutree.h | 25 -
kernel/rcutree_plugin.h | 48 +-
kernel/rcutree_trace.c | 12
10 files changed, 690 insertions(+), 531 deletions(-)


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