[PATCH v6 0/4] rcu: call_rcu() power improvements

["Joel Fernandes (Google)" <joel@joelfernandes.org>]

v6 version of RCU lazy patches based on rcu/next branch.

To facilitate easier merge, I dropped tracing and other patches and just
implemented the new changes. I will post the tracing patches later along with
rcutop as I need to add new tracepoints that Frederic suggested.

Main changes:
1. rcu_barrier() wake up only for lazy bypass list.
2. Make all call_rcu() default-lazy and add call_rcu_flush() API.
3. Take care of some callers using call_rcu_flush() API.

I am seeing good performance and power with these patches on real ChromeOS x86
asymmetric hardware.

v5 cover letter is here:
https://lore.kernel.org/all/20220901221720.1105021-1-joel@joelfernandes.org/

Joel Fernandes (Google) (3):
rcu: Make call_rcu() lazy to save power
rcuscale: Add laziness and kfree tests
percpu-refcount: Use call_rcu_flush() for atomic switch

Vineeth Pillai (1):
rcu: shrinker for lazy rcu

include/linux/rcupdate.h |   7 ++
kernel/rcu/Kconfig       |   8 ++
kernel/rcu/rcu.h         |   8 ++
kernel/rcu/rcuscale.c    |  65 ++++++++++-
kernel/rcu/tiny.c        |   2 +-
kernel/rcu/tree.c        | 133 ++++++++++++++--------
kernel/rcu/tree.h        |  17 ++-
kernel/rcu/tree_exp.h    |   2 +-
kernel/rcu/tree_nocb.h   | 236 +++++++++++++++++++++++++++++++++------
lib/percpu-refcount.c    |   3 +-
10 files changed, 395 insertions(+), 86 deletions(-)

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2.37.3.998.g577e59143f-goog