Re: [Xen-ia64-devel][PATCH] Enable SMP on VTI domain.

[Tristan Gingold <Tristan.Gingold@xxxxxxxx>]

Le Mercredi 31 Mai 2006 15:02, Xu, Anthony a écrit :
> From: Tristan Gingold [mailto:Tristan.Gingold@xxxxxxxx]
>
> >Sent: 2006年5月31日 20:54
> >To: Xu, Anthony; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >Subject: Re: [Xen-ia64-devel][PATCH] Enable SMP on VTI domain.
> >
> >Le Mercredi 31 Mai 2006 14:25, Xu, Anthony a écrit :
> >> From: Tristan Gingold [mailto:Tristan.Gingold@xxxxxxxx]
> >>
> >> >Sent: 2006年5月31日 20:19
> >> >To: Xu, Anthony; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >> >Subject: Re: [Xen-ia64-devel][PATCH] Enable SMP on VTI domain.
> >> >
> >> >Le Mercredi 31 Mai 2006 14:04, Xu, Anthony a écrit :
> >> >> From: Tristan Gingold
> >> >>
> >> >> >Sent: 2006年5月31日 20:04
> >> >> >To: Xu, Anthony; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >> >> >Subject: Re: [Xen-ia64-devel][PATCH] Enable SMP on VTI domain.
> >> >> >
> >> >> >Le Mercredi 31 Mai 2006 13:43, Xu, Anthony a écrit :
> >> >> >> From: Tristan Gingold [mailto:Tristan.Gingold@xxxxxxxx]
> >> >> >
> >> >> >[...]
> >> >> >
> >> >> >> >> Another concern is,
> >> >> >> >> If SMP guest is running on a UP platform, vcpus may have same
> >> >> >> >> vcpuid.
> >> >> >> >
> >> >> >> >Why ?  IMHO this can never happen.
> >> >> >>
> >> >> >> There are 4 LP on my box, if I want to boot a domU with 6 vcpus,
> >> >> >> Can this domU boot?
> >> >> >
> >> >> >[ I have never tried, but here is my understanding:]
> >> >> >Sure.  You can create more vcpus than existing cpus.  Of course, you
> >> >> > can't run 6 vcpus simultaneously on 4 cpus!
> >> >>
> >> >> If the lid of vcpus is extracted from machine lid, there are at least
> >> >> two vcpus whose lids are same, which may make guest OS confused.
> >> >
> >> >lid are paravirtualized except for dom0 (currently, this has to be
> >> > revisited).
> >> >
> >> >I think there is a misunderstanding somewhere, because some questions
> >> > sound too strange.
> >> >
> >> >My (small) comment was simple:
> >> >On Xen/VTI, GFW set lid and Xen has to build a map from lid to vcpuid.
> >> >I just think it should be simpler to modify GFW so that lid = vcpuid.
> >>
> >> That is exactly what I implemented.
> >
> >I may have mis-read the patches you have recently posted but on the
> > current changeset lid_to_vcpu is O(n).  Why isn't it O(1) ?
>
> Sorry, don’t catch you.
> In lid register, id is from 24 to 31, eid is from 16 to 23.
> So lid = vcpuid << 24
OK.

Tristan.

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