Re: [PATCH 2/4] sched: Isolate preempt counting in its own config option

Peter Zijlstra
2011-06-08T20:05:42Z

On Wed, 2011-06-08 at 12:58 -0700, Paul E. McKenney wrote:
>
> On Wed, Jun 08, 2011 at 09:47:14PM +0200, Peter Zijlstra wrote:
> > On Wed, 2011-06-08 at 19:48 +0200, Frederic Weisbecker wrote:
> > >
> > > Create a new CONFIG_PREEMPT_COUNT that handles the inc/dec
> > > of preempt count offset independently. So that the offset
> > > can be updated by preempt_disable() and preempt_enable()
> > > even without the need for CONFIG_PREEMPT beeing set.
> > >
> > > This prepares to make CONFIG_DEBUG_SPINLOCK_SLEEP working
> > > with !CONFIG_PREEMPT where it currently doesn't detect
> > > code that sleeps inside explicit preemption disabled
> > > sections.
> >
> > The last time this got proposed it got shot down due to the extra
> > inc/dec stuff all over the place increasing overhead significantly.
>
> Even given that the extra inc/dec stuff only happens in kernels built
> with DEBUG_SPINLOCK_SLEEP=y (DEBUG_ATOMIC_SLEEP=y after patch 4/4)?

Ah, no that might be ok. That's what I get for trying to read email in
no time.