linux-kernel - Re: [GIT PULL] timers/nohz updates for 3.12

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Date:	Mon, 12 Aug 2013 20:44:28 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	Li Zhong <zhong@...ux.vnet.ibm.com>,
	Mike Galbraith <efault@....de>,
	Kevin Hilman <khilman@...aro.org>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Alex Shi <alex.shi@...el.com>, Paul Turner <pjt@...gle.com>,
	Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [GIT PULL] timers/nohz updates for 3.12


* Frederic Weisbecker <fweisbec@...il.com> wrote:

> Ingo,
> 
> Please pull the timers/nohz branch that can be found at:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> 	timers/nohz
> 
> It mostly contains fixes and full dynticks off-case optimizations. I believe that
> distros want to enable this feature so it seems important to optimize the case
> where the "nohz_full=" parameter is empty. ie: I'm trying to remove any performance
> regression that comes with NO_HZ_FULL=y when the feature is not used.
> 
> This patchset improves the current situation a lot (off-case appears to be around 11% faster
> with hackbench, although I guess it may vary depending on the configuration but it should be
> significantly faster in any case) now there is still some work to do: I can still observe a
> remaining loss of 1.6% throughput seen with hackbench compared to CONFIG_NO_HZ_FULL=n
> 
> Thanks,
> 	Frederic
> ---
> 
> Frederic Weisbecker (23):
>       sched: Consolidate open coded preemptible() checks
>       context_tracing: Fix guest accounting with native vtime
>       vtime: Update a few comments
>       context_tracking: Fix runtime CPU off-case
>       nohz: Only enable context tracking on full dynticks CPUs
>       context_tracking: Remove full dynticks' hacky dependency on wide context tracking
>       context_tracking: Ground setup for static key use
>       context_tracking: Optimize main APIs off case with static key
>       context_tracking: Optimize guest APIs off case with static key
>       context_tracking: Optimize context switch off case with static keys
>       context_tracking: User/kernel broundary cross trace events
>       vtime: Remove a few unneeded generic vtime state checks
>       vtime: Fix racy cputime delta update
>       context_tracking: Split low level state headers
>       hardirq: Split preempt count mask definitions
>       m68k: hardirq_count() only need preempt_mask.h
>       vtime: Describe overriden functions in dedicated arch headers
>       vtime: Optimize full dynticks accounting off case with static keys
>       vtime: Always scale generic vtime accounting results
>       vtime: Always debug check snapshot source _before_ updating it
>       nohz: Rename a few state variables
>       nohz: Optimize full dynticks state checks with static keys
>       nohz: Optimize full dynticks's sched hooks with static keys
> 
> 
>  arch/ia64/include/asm/Kbuild            |    1 +
>  arch/m68k/include/asm/irqflags.h        |    2 +-
>  arch/powerpc/include/asm/Kbuild         |    1 +
>  arch/s390/include/asm/cputime.h         |    3 -
>  arch/s390/include/asm/vtime.h           |    7 ++
>  arch/s390/kernel/vtime.c                |    1 +
>  include/linux/context_tracking.h        |  120 +++++++++++++++--------------
>  include/linux/context_tracking_state.h  |   39 +++++++++
>  include/linux/hardirq.h                 |  117 +----------------------------
>  include/linux/preempt_mask.h            |  122 +++++++++++++++++++++++++++++
>  include/linux/tick.h                    |   45 +++++++++--
>  include/linux/vtime.h                   |   74 ++++++++++++++++--
>  include/trace/events/context_tracking.h |   58 ++++++++++++++
>  init/Kconfig                            |   28 +++++--
>  kernel/context_tracking.c               |  128 ++++++++++++++++++-------------
>  kernel/sched/core.c                     |    4 +-
>  kernel/sched/cputime.c                  |   53 ++++---------
>  kernel/time/Kconfig                     |    1 -
>  kernel/time/tick-sched.c                |   56 ++++++--------
>  19 files changed, 534 insertions(+), 326 deletions(-)

When merged to -tip it causes this build error:

 kernel/time/tick-sched.c:186:3: error: 'have_nohz_full_mask' undeclared (first use in this function)
 kernel/time/tick-sched.c:345:2: error: 'cpu' undeclared (first use in this function)

config attached.

I did what looked like to be an obvious conflict resolution to 
tick-sched.c (attached), please double check that too.

While at it, mind rebasing your changes to tip:timers/urgent, which has a 
few nohz fixes pending as well?

Thanks,

	Ingo

View attachment "config" of type "text/plain" (94404 bytes)

View attachment "tick-sched.c" of type "text/plain" (30035 bytes)