Re: [PATCH v2 0/2] xen: credit2: fix boot hangs if dom0_nodes is used

[Jan Beulich <jbeulich@xxxxxxxx>]

On 03.08.2022 11:58, Dario Faggioli wrote:
> Take 2 of this series. I think I've addressed Jan's comments. v1 was
> Message-id: <165944775952.3531.14547627248752689801.stgit@tumbleweed.Wayrath>
> 
> Currently, if the dom0_nodes parameter is used, to limit the hard or
> soft affinity of dom0's vCPUs, the boot hangs. This is because the vCPU
> affinity is set in two steps, and is only correct after we've done both.
> Credit2, however, manages to see and use the result of the first one and
> vCPUs are put on pCPUs where they can't run.
> 
> This has been reported here:
> https://bugzilla.suse.com/show_bug.cgi?id=1197081
> 
> And a fix has been discussed in the thread of this message:
> https://lore.kernel.org/xen-devel/e061a647cd77a36834e2085a96a07caa785c5066.camel@xxxxxxxx/
> 
> The solution adopted in this series is to change the vCPU affinity
> setting code in such a way that it happens alltogether and in one place
> (patch 2).
> 
> While there, make the dom0_vcpus_pin boot parameter more precise, by
> making sure that it is applied only to actual dom0's vCPUs, and not to
> the vCPUs of the hardware domain, which may or may not be dom0 itself
> (patch 2).
> 
> Regards
> ---
> Dario Faggioli (2):
>       xen: sched: dom0_vcpus_pin should only affect dom0

I'll throw in this one, but ...

>       xen/sched: setup dom0 vCPUs affinity only once

... I'd like to give this a little for a Tested-by: Olaf to possibly
arrive.

Jan