Re: [RFC 2/3] kernel/cpu: Mark nonboot cpus as inactive when shutting down nonboot cpus

[Pingfan Liu]

On Wed, Oct 29, 2025 at 8:13 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> On Wed, Oct 29 2025 at 19:36, Pingfan Liu wrote:
> > On Tue, Oct 28, 2025 at 01:59:11PM +0100, Thomas Gleixner wrote:
> >> If you freeze stuff there is nothing to do. Hibernation works exactly
> >> that way without any magic hacks in a particular scheduling class, no?
> >>
> >
> > There is a nuance: DL bandwidth represents a commitment, not necessarily
> > the actual payload. Even a blocked DL task still occupies DL bandwidth.
> > The system's DL bandwidth remains unchanged as long as the CPUs stay
> > online, which is the case in hibernation.
>
> No. Hibernation brings the non-boot CPUs down in order to create the
> disk image.
>

Oh, I see. Since there are no DL tasks in the runqueue, no migration
occurs to activate the DL bandwidth. This approach, similar to PM, is
perfect for addressing this issue.


Thanks,

Pingfan