linux-kernel - [GIT PULL] nohz: Adaptively stop the tick, finally

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Date:	Mon, 22 Apr 2013 20:59:36 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Chris Metcalf <cmetcalf@...era.com>,
	Christoph Lameter <cl@...ux.com>,
	Geoff Levand <geoff@...radead.org>,
	Gilad Ben Yossef <gilad@...yossef.com>,
	Hakan Akkan <hakanakkan@...il.com>,
	Kevin Hilman <khilman@...aro.org>,
	Li Zhong <zhong@...ux.vnet.ibm.com>,
	Oleg Nesterov <oleg@...hat.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Stephane Eranian <eranian@...gle.com>,
	Jiri Olsa <jolsa@...hat.com>
Subject: [GIT PULL] nohz: Adaptively stop the tick, finally

Ingo,

Please pull the latest full dynticks branch that can found at:

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

HEAD: 67826eae8c16dbf00c262be6ec15021bb42f69c4

This handles perf and CPUs that get more than one task and fix posix cpu timers
handling.

This can finally stop the tick. It boots and doesn't crash, as far as I tested.

Now what's left:

* Kick CPUs' tick when the clock is marked unstable

* Kick CPUs when they extend the RCU grace periods too much by staying in
the kernel for too long (we are discussing this with Paul).

* sched_class:task_tick(). There are gazillions statistics maintained there.
It's probably mostly about local and global fairness. May be for other stuff
too (cgroups, etc...).

* update_cpu_load_active(): again, various stats maintained there

* load balancing (see trigger_load_balance() usually called from the tick).

I hope we can handle these things progressively in the long run.

Thanks.

---
Frederic Weisbecker (10):
  posix_timers: Fix pre-condition to stop the tick on full dynticks
  perf: Kick full dynticks CPU if events rotation is needed
  perf: New helper to prevent full dynticks CPUs from stopping tick
  sched: Kick full dynticks CPU that have more than one task enqueued.
  sched: New helper to prevent from stopping the tick in full dynticks
  nohz: Re-evaluate the tick from the scheduler IPI
  nohz: Implement full dynticks kick
  nohz: Prepare to stop the tick on irq exit
  nohz: Re-evaluate the tick for the new task after a context switch
  nohz: Disable the tick when irq resume in full dynticks CPU

 include/linux/perf_event.h |    6 +++
 include/linux/sched.h      |    6 +++
 include/linux/tick.h       |    4 ++
 kernel/events/core.c       |   17 +++++++-
 kernel/posix-cpu-timers.c  |    6 +-
 kernel/sched/core.c        |   24 +++++++++++-
 kernel/sched/sched.h       |   11 +++++
 kernel/softirq.c           |   19 ++++++--
 kernel/time/tick-sched.c   |   95 ++++++++++++++++++++++++++++++++++++++-----
 9 files changed, 167 insertions(+), 21 deletions(-)

-- 
1.7.5.4

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