Re: Priority Inheritance Test (Real-Time Preemption)

Bill Huey
2004-11-22T21:48:18Z

On Mon, Nov 22, 2004 at 09:16:18AM -0500, john cooper wrote:
> I'd hazard a guess the reason existing implementations do not
> do this type of dependency-chain closure is the complexity of a
> general approach. Getting correct behavior and scaling on SMP
> require some restrictions of how lock ownership is maintained,
> otherwise fine grained locking is not possible. Another likely

What do you mean by that ? Are you talking about strict priority
obedience by the system ?

> reason is the fact more mechanism is getting put in place for
> less likely inversion scenarios. And when those scenarios do
> exist the cost of effecting promotion closure may well be
> greater than allowing the priority inversions to subside.
> However this point of diminishing returns is application
> dependent so there is no single, simple solution.

Yes, this is my point.

> That said I don't see anything in the current work which precludes
> doing any of the above. To my eyes, the groundwork is already
> in place.

Yes it is. :)

bill