Re: [Xen-devel] [PATCH] cpupools: retry cpupool-destroy if domain in cpupool is dying

[Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>]

On 14.05.2014 15:13, Jan Beulich wrote:
> > > > On 14.05.14 at 15:05, <juergen.gross@xxxxxxxxxxxxxx> wrote:
> > On 14.05.2014 14:28, Jan Beulich wrote:
> > > > > > On 14.05.14 at 12:35, <juergen.gross@xxxxxxxxxxxxxx> wrote:
> > > > sched_destroy_vcpu() and sched_destroy_domain() have to happen before
> > > > cpupool_rm_domain(). This could be avoided if the domain would be moved to
> > > > cpupool0 in domain_destroy().
> > > >
> > > > Hmm, doesn't sound too bad. This would be just symmetrical to domain
> > > > creation. What do you think?
> > > I'm always in favor of symmetry, where possible and suitable. So
> > > unless George objects or sees problems with this, why don't you
> > > give this a try?
> > One problem arises: sched_move_domain() can fail. Is there a preferred way to
> > handle this situation in domain_destroy() ? I could try to defer destroying
> > the domain until sched_move_domain() succeeds, but using a busy loop doing this
> > seems contra-productive and a timer based solution requires a timer
> > structure.
> >
> > I could reuse the domain watchdog_timer entries if I move
> > watchdog_domain_destroy() to domain_destroy() (which seems to be not critical).
> >
> > OTOH this seems a little bit hacky...
> Indeed it does. Yet - does that move have to happen in
> domain_destroy()? I.e. can't it be pulled even further ahead into
> domain_kill()? That one already is preemptable/resumable (via
> guarantees we expect from the tools side iirc), since
> domain_relinquish_resources() may take quite long a time. Of course
> that'll work only if no failure condition in sched_move_domain() is
> permanent.
Aah, excellent!

Now the patch seems to be very simple! I'll do some tests to verify it isn't
breaking something.


Juergen

--
Juergen Gross                 Principal Developer Operating Systems
PSO PM&D ES&S SWE OS6                  Telephone: +49 (0) 89 62060 2932
Fujitsu                                   e-mail: juergen.gross@xxxxxxxxxxxxxx
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D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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