Re: [PATCH v2 01/12] sched: Simplify INIT_PREEMPT_COUNT

From	Frederic Weisbecker <fweisbec@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 01/12] sched: Simplify INIT_PREEMPT_COUNT
Date	2015-10-01 15:30 +0200
Message-ID	<qeM5P-5zC-1@gated-at.bofh.it> (permalink)
References	<qek9A-6Kx-13@gated-at.bofh.it> <qek9C-6Kx-67@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Sep 30, 2015 at 09:10:36AM +0200, Peter Zijlstra wrote:
> As per commit d86ee4809d03 ("sched: optimize cond_resched()") we need
> PREEMPT_ACTIVE to avoid cond_resched() from working before the
> scheduler is setup.
> 
> However, keeping preemption disabled should do the same thing already,
> making the PREEMPT_ACTIVE part entirely redundant.
> 
> The only complication is !PREEMPT_COUNT kernels, where
> PREEMPT_DISABLED ends up being 0. Instead we use an unconditional
> PREEMPT_OFFSET to set preempt_count() even on !PREEMPT_COUNT kernels.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>

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[PATCH v2 00/12] sched: Killing PREEMPT_ACTIVE Peter Zijlstra <peterz@infradead.org> - 2015-09-30 09:40 +0200
  [PATCH v2 04/12] sched: Add preempt argument to __schedule() Peter Zijlstra <peterz@infradead.org> - 2015-09-30 09:40 +0200
  [PATCH v2 06/12] sched: Stop setting PREEMPT_ACTIVE Peter Zijlstra <peterz@infradead.org> - 2015-09-30 09:40 +0200
    Re: [PATCH v2 06/12] sched: Stop setting PREEMPT_ACTIVE Frederic Weisbecker <fweisbec@gmail.com> - 2015-10-01 17:30 +0200
  [PATCH v2 08/12] sched: Simplify preempt_count tests Peter Zijlstra <peterz@infradead.org> - 2015-09-30 09:40 +0200
    Re: [PATCH v2 08/12] sched: Simplify preempt_count tests Frederic Weisbecker <fweisbec@gmail.com> - 2015-10-01 17:40 +0200
  [PATCH v2 12/12] sched: Add preempt_count invariant check Peter Zijlstra <peterz@infradead.org> - 2015-09-30 09:40 +0200
    Re: [PATCH v2 12/12] sched: Add preempt_count invariant check Steven Rostedt <rostedt@goodmis.org> - 2015-09-30 11:40 +0200
      Re: [PATCH v2 12/12] sched: Add preempt_count invariant check Peter Zijlstra <peterz@infradead.org> - 2015-09-30 13:20 +0200
  [PATCH v2 11/12] sched: More notrace Peter Zijlstra <peterz@infradead.org> - 2015-09-30 09:40 +0200
  [PATCH v2 01/12] sched: Simplify INIT_PREEMPT_COUNT Peter Zijlstra <peterz@infradead.org> - 2015-09-30 09:40 +0200
    Re: [PATCH v2 01/12] sched: Simplify INIT_PREEMPT_COUNT Steven Rostedt <rostedt@goodmis.org> - 2015-09-30 11:10 +0200
      Re: [PATCH v2 01/12] sched: Simplify INIT_PREEMPT_COUNT Thomas Gleixner <tglx@linutronix.de> - 2015-09-30 22:50 +0200
    Re: [PATCH v2 01/12] sched: Simplify INIT_PREEMPT_COUNT Frederic Weisbecker <fweisbec@gmail.com> - 2015-10-01 15:30 +0200

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