Re: [PATCH V3 0/4] genirq/affinity: irq vector spread among online CPUs as far as possible

[Dou Liyang]

Hi Rafael,

Thank you so much for your reply.

At 03/13/2018 05:25 PM, Rafael J. Wysocki wrote:
> On Tue, Mar 13, 2018 at 4:11 AM, Dou Liyang <douly.fnst@xxxxxxxxxxxxxx> wrote:
> > Hi Thomas,
> >
> > At 03/09/2018 11:08 PM, Thomas Gleixner wrote:
> > [...]
> > > I'm not sure if there is a clear indicator whether physcial hotplug is
> > > supported or not, but the ACPI folks (x86) and architecture maintainers
> >
> > +cc Rafael
> >
> > > should be able to answer that question. I have a machine which says:
> > >
> > >      smpboot: Allowing 128 CPUs, 96 hotplug CPUs
> > >
> > > There is definitely no way to hotplug anything on that machine and sure
> > > the
> >
> >
> > AFAIK, in ACPI based dynamic reconfiguration, there is no clear
> > indicator. In theory, If the ACPI tables have the hotpluggable
> > CPU resources, the OS can support physical hotplug.
>
> In order for the ACPI-based CPU hotplug (I mean physical, not just the
> software offline/online we do in the kernel) to work, there have to be
> objects in the ACPI namespace corresponding to all of the processors
> in question.
>
> If they are not present, there is no way to signal insertion and eject
> the processors safely.

Yes, I see.

Thanks
	dou

>