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RE: [PATCH 5/5] sched/arinc653: Implement CAST-32A multicore scheduling
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Jeff Kubascik <Jeff.Kubascik@xxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Stewart Hildebrand <Stewart.Hildebrand@xxxxxxxxxxxxxxx>
- Date: Thu, 17 Sep 2020 14:57:08 +0000
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- Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxx>, Josh Whitehead <Josh.Whitehead@xxxxxxxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Dario Faggioli <dfaggioli@xxxxxxxx>
- Delivery-date: Thu, 17 Sep 2020 14:57:23 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: [PATCH 5/5] sched/arinc653: Implement CAST-32A multicore scheduling
On Thursday, September 17, 2020 10:43 AM, Andrew Cooper wrote:
>On 16/09/2020 19:18, Jeff Kubascik wrote:
>> +/*
>> + * A handle with all zeros represents domain 0 if present, otherwise idle
>> UNIT
>> + */
>> +#define DOM0_HANDLE ((const xen_domain_handle_t){0})
>
>This isn't accurate.
>
>There are systems where dom0 doesn't have a zero UUID (XenServer for
>one), and its easy to create domU's which have a zero UUID. They are
>not unique, and can be changed at any time during the running of the VM.
>
>If you need a unique identifier, then use domid's.
>
>I can't see any legitimate need for the scheduler to handle the UUID at all.
We tried switching it to domid at one point in the past, but the problem was
that when a domU reboots (destroy/create) the domid increments, so the schedule
would have to be reinstantiated. At least that was the case before a recent
patch series allowing to specify domid [1], but Jeff developed this CAST-32A
series prior to that. The UUID can be specified in the .cfg file, allowing
domUs to reboot and come back up with the same UUID.
Stew
[1] https://lists.xenproject.org/archives/html/xen-devel/2020-02/msg01574.html
>~Andrew
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