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SubjectRe: [Fwd: lost need_resched flag re-introduced?]
kuznet@ms2.inr.ac.ru wrote:
>
> Hello!
>
> > > A while back I reported the lost need_resched flag bug ( it happens if
> > > need_resched is set right before switch_to() is called). Later on a one-line
> > > fix is added to __schedule_tail().
> > >
> > > current->need_resched |= prev->need_resched;
> > >
> > > I looked at the latest kernel and found this one is gone. Is the lost
> > > need_resched problem taken care of in some other way? Or is it re-introduced?
>
> It is removed not only because it was wrong (which you have found too),
> but because it was useless even if copied correctly.
>
> current->need_resched is not changed in interrupt context outside
> runqueue lock except for scheduler timer, where copying results
> in nothing but spurious reschedule.
>
> Alexey

Alexey,

I think wake_up_process() is called in interrupt routine quite often and it
will set need_resched flag (through reschedule_idle()). ???

I did several run time tests and confirmed the missing need_resched flag was
happening. Ether some new code takes care of it. Or it is still there.

Jun
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