Re: pserialize_switchpoint() question

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Thu, Jul 19, 2018 at 01:43:56PM +0200, Manuel Bouyer wrote:
> Hello,
> while debugging why XEN domU kernels hang on psrlz, I found that, when
> this happens, pserialize_switchpoint() seems to not be called for one of the
> CPUs (not always the same). The CPU in question doens't show up in
> psz->psz_pass. I also noticed that sometimes, pserialize_perform() seems
> to take much longer (several seconds) than it should.
> 
> Now my question: how is pserialize_switchpoint() supposed to be called ?
> I see it's called from softint_dispatch() but Xen doesn't use it
> (no fast soft interrupts).
> I see it's called from lwp_startup() and mi_switch(), but only if
> there is a context switch. If the CPU is idle, it will never be called.

This is also true if a single cpu-bound process is running on the CPU ...

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--