[Adeos-main] Re: [SMP-BUG?] inconsistent cpuid after dispatch_wired

[Philippe Gerum <rpm@xenomai.org>]

On Mon, 2006-12-18 at 13:10 +0100, Jan Kiszka wrote:
> Hi Philippe,
> 
> actually, I was trying to apply a micro-optimisation on
> __ipipe_handle_irq, but I think I also found a bug on SMP systems (at
> least on x86):
> 
> After __ipipe_handle_irq forwarded some IRQ to __ipipe_dispatch_wired
> and the latter returned 1 (i.e. "not deferred"), a pipeline sync is
> triggered using the cpuid read on IRQ entry. But I think that
> __ipipe_dispatch_wired may very well have caused some CPU migration of
> the current context so that reloading the cpuid is required here. This
> is what the first attached patch does.
> 

Correct. Applied, thanks.

> Jan
> 
> 
> PS: The optimisation I was looking at deals with the assumption that a
> wired IRQ may never be also a sticky one, correct?

Correct.

>  If yes, the second
> (alternative) patch might be interesting as it avoids to touch the root
> domain data structure and to test for stickiness in the wired case.
> Should shorten the wired IRQ path by a few cycles (or more on cache
> miss...).

Applied, thanks.

-- 
Philippe.