linux-kernel - [GIT PULL] nohz: Tick dependency mask

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Date:	Mon, 15 Feb 2016 02:08:40 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Chris Metcalf <cmetcalf@...hip.com>,
	Luiz Capitulino <lcapitulino@...hat.com>,
	Christoph Lameter <cl@...ux.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Rik van Riel <riel@...hat.com>
Subject: [GIT PULL] nohz: Tick dependency mask

Ingo, Thomas,

Please pull the timers/core-v8 branch that can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
	timers/core-v8

HEAD: 0378c8b4f541116843c5d19b403bb6145fa1030e

---
Currently in nohz full configs, the tick dependency is checked
asynchronously by nohz code from interrupt and context switch for each
concerned subsystem with a set of function provided by these. Such
functions are made of many conditions and details that can be heavyweight
as they are called on fastpath: sched_can_stop_tick(),
posix_cpu_timer_can_stop_tick(), perf_event_can_stop_tick()...

Thomas suggested a few month ago to make that tick dependency check
synchronous. Instead of checking subsystems details from each interrupt
to guess if the tick can be stopped, every subsystem that may have a tick
dependency should set itself a flag specifying the state of that
dependency. This way we can verify if we can stop the tick with a single
lightweight mask check on fast path.

This conversion from a pull to a push model to implement tick dependency
is the core feature of this patchset that is split into:

* Nohz wide kick simplification
* Improve nohz tracing
* Introduce tick dependency mask
* Migrate scheduler, posix timers, perf events and sched clock tick
  dependencies to the tick dependency mask.


Thanks,
	Frederic
---

Frederic Weisbecker (9):
      atomic: Export fetch_or()
      nohz: Implement wide kick on top of irq work
      nohz: New tick dependency mask
      nohz: Use enum code for tick stop failure tracing message
      perf: Migrate perf to use new tick dependency mask model
      sched: Account rr tasks
      sched: Migrate sched to use new tick dependency mask model
      posix-cpu-timers: Migrate to use new tick dependency mask model
      sched-clock: Migrate to use new tick dependency mask model


 include/linux/atomic.h         |  21 +++++
 include/linux/perf_event.h     |   6 --
 include/linux/posix-timers.h   |   3 -
 include/linux/sched.h          |  11 ++-
 include/linux/tick.h           |  97 ++++++++++++++++++++++-
 include/trace/events/timer.h   |  36 +++++++--
 kernel/events/core.c           |  65 +++++++++++----
 kernel/sched/clock.c           |   5 ++
 kernel/sched/core.c            |  49 +++++-------
 kernel/sched/rt.c              |  16 ++++
 kernel/sched/sched.h           |  48 +++++++----
 kernel/time/posix-cpu-timers.c |  52 +++---------
 kernel/time/tick-sched.c       | 175 ++++++++++++++++++++++++++++++++---------
 kernel/time/tick-sched.h       |   1 +
 14 files changed, 424 insertions(+), 161 deletions(-)