Re: [RFC][PATCH] irq_work -v2

Peter Zijlstra
2010-06-25T19:49:24Z

On Fri, 2010-06-25 at 21:39 +0200, Peter Zijlstra wrote:
> On Fri, 2010-06-25 at 21:30 +0200, Andi Kleen wrote:
> >
> > I'm not sure what all the logic for entry enqueued by someone
> > else is good for? Is that for the case you don't have enough
> > entries preallocated and you share them with someone else?
> >
> > Normally if the sharing is per cpu that would be difficult
> > to recover from because if it's due to a nest situation (for example)
> > you would deadlock.
> >
> > For me it would seem simpler to simply not share.
>
> perf has two different reasons to for the callback, what I do is set the
> state and enqueue, if its already enqueued the pending callback will
> handle both.
>
> Its cheaper than having two callback structures per event.
>
> We can expose the claim/enqueue thing separately so that users can
> choose.

Also, its possible the PMI hits again before the IRQ callback has a
chance to happen.