rcu/nocb: De-offload and re-offload support v3

From:		Frederic Weisbecker <frederic-AT-kernel.org>
To:		LKML <linux-kernel-AT-vger.kernel.org>
Subject:		[PATCH 00/16] rcu/nocb: De-offload and re-offload support v3
Date:		Fri, 23 Oct 2020 16:46:33 +0200
Message-ID:		<20201023144649.53046-1-frederic@kernel.org>
Cc:		Frederic Weisbecker <frederic-AT-kernel.org>, Steven Rostedt <rostedt-AT-goodmis.org>, Mathieu Desnoyers <mathieu.desnoyers-AT-efficios.com>, "Paul E . McKenney" <paulmck-AT-kernel.org>, Lai Jiangshan <jiangshanlai-AT-gmail.com>, Neeraj Upadhyay <neeraju-AT-codeaurora.org>, Joel Fernandes <joel-AT-joelfernandes.org>, Josh Triplett <josh-AT-joshtriplett.org>
Archive-link:		Article

Hi,

This is the third attempt to make rcu-nocb mutable at runtime. See
v2 there: https://lwn.net/Articles/832031/

Many fixes included and rcutorture support:

03: Whitespace fix
04: Add "rcu/nocb: Always init segcblist on CPU up" (Thanks rcutorture!)
05: Add return value for failure on (de)offloading
06: Add "rcu/nocb: Don't deoffload an offline CPU with pending work" (Thanks Paul!)
12: Add "rcu/nocb: Only cond_resched() from actual offloaded batch processing" (Thanks rcutorture!)
14: Write a real and more self-confident changelog
15/16: Add rcutorture support (thanks Paul!)

My last remaining worry, as exposed in 13/16, is that __call_rcu_core()
isn't called during transition states. I need to see how I can handle
that.

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
	rcu/nocb-toggle-v2

HEAD: 0247cd09fd48a38741e5cc6634810985b405baca

Thanks,
	Frederic
---

Frederic Weisbecker (15):
      rcu: Implement rcu_segcblist_is_offloaded() config dependent
      rcu: Turn enabled/offload states into a common flag
      rcu: Provide basic callback offloading state machine bits
      rcu/nocb: Always init segcblist on CPU up
      rcu: De-offloading CB kthread
      rcu/nocb: Don't deoffload an offline CPU with pending work
      rcu: De-offloading GP kthread
      rcu: Re-offload support
      rcu: Shutdown nocb timer on de-offloading
      rcu: Flush bypass before setting SEGCBLIST_SOFTIRQ_ONLY
      rcu: Set SEGCBLIST_SOFTIRQ_ONLY at the very last stage of de-offloading
      rcu/nocb: Only cond_resched() from actual offloaded batch processing
      rcu: Process batch locally as long as offloading isn't complete
      rcu: Locally accelerate callbacks as long as offloading isn't complete
      tools/rcutorture: Support nocb toggle in TREE01

Paul E. McKenney (1):
      rcutorture: Test runtime toggling of CPUs' callback offloading


 Documentation/admin-guide/kernel-parameters.txt    |   8 +
 include/linux/rcu_segcblist.h                      | 119 +++++++-
 include/linux/rcupdate.h                           |   4 +
 kernel/rcu/rcu_segcblist.c                         |  13 +-
 kernel/rcu/rcu_segcblist.h                         |  45 ++-
 kernel/rcu/rcutorture.c                            |  86 +++++-
 kernel/rcu/tree.c                                  |  47 +--
 kernel/rcu/tree.h                                  |   2 +
 kernel/rcu/tree_plugin.h                           | 330 +++++++++++++++++++--
 .../selftests/rcutorture/configs/rcu/TREE01.boot   |   4 +-
 10 files changed, 603 insertions(+), 55 deletions(-)