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SubjectRe: [RFC PATCH] rcu: don't ignore preempt_disable() in the idle loop
On Wed, Mar 10, 2010 at 10:13:56AM +0800, Lai Jiangshan wrote:
> Paul E. McKenney wrote:
> >>
> >> This is another try, it uses the fact that idle loops
> >> are executing with preept_count()=1.
> >> But I didn't look deep into all idle loops.
> >
> > Hello, Lai!
> >
> > One question below...
> >
> > Thanx, Paul
> >
>
> [...]
>
> >> +
> >> + if ((preempt_count() & PREEMPT_MASK) > IDLE_CORE_LOOP_PREEMPT_COUNT)
> >> + return 0;
> >
> > How does this work in CONFIG_PREEMPT=n kernels? I don't see how it
> > does, regardless of what preempt_count() returns in this case.
>
> You are right, It cannot work in CONFIG_PREEMPT=n kernels.
> ignore this stupid patch.

Don't be too hard on yourself -- it is an interesting idea, just doesn't
seem to quite work out. Perhaps it will lead you to another idea that
does work.

Thanx, Paul


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