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Re: [Xen-devel] [PATCH 0/3] xen/sched: use new idle scheduler for free cpus

On 13.08.19 17:51, Dario Faggioli wrote:
On Fri, 2019-08-02 at 15:07 +0200, Juergen Gross wrote:
These three patches have been carved out from my core scheduling
as they are sufficiently independent to be applied even without the

Without this little series there are messages like the following to
seen on the console when booting with smt=0:

(XEN) Adding cpu 1 to runqueue 0
(XEN) CPU 1 still not dead...
(XEN) CPU 1 still not dead...
(XEN) CPU 1 still not dead...
(XEN) CPU 1 still not dead...

By assigning cpus to Cpupool-0 only after all cpus are up and by not
using the more complicated credit2 scheduler for cpus not in any
cpupool this situation can simply no longer happen, as parking the
to be started threads is done before.

And this is not the only problem, solved by this series (or an
equivalent approach).

Right now, CPUs that are not in any pool, still belong to Pool-0's
scheduler. This forces us to make, within the scheduler, extra effort
to avoid actually running vCPUs on those.

In the case of Credit1, this also cause issue to weights
(re)distribution, as the number of CPUs available to the scheduler is

So, we absolutely want something like this.

This is described in the changelog of commit e7191920261d ("xen:
credit2: never consider CPUs outside of our cpupool").

Would it be possible to mention this in one of the changelogs of the
series (patch 3 would be the best place, I think).



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