Re: [Xen-devel] [PATCH RFC] xen-time: decreasing the rating of the xen clocksource below that of the tsc clocksource for dom0's

[Jan Beulich]

>>> On 07.01.15 at 17:30, <Ian.Campbell@xxxxxxxxxx> wrote:
> On Wed, 2015-01-07 at 17:16 +0100, Imre Palik wrote:
>> From: "Palik, Imre" <imrep@xxxxxxxxx>
>> 
>> In Dom0's the use of the TSC clocksource (whenever it is stable enough to
>> be used) instead of the Xen clocksource should not cause any issues, as
>> Dom0 VMs never live-migrated.
> 
> Is this still true given that dom0's vcpus are migrated amongst pcpus on
> the host? The tsc are not synchronised on some generations of hardware
> so the result there would be the TSC appearing to do very odd things
> under dom0's feet. Does Linux cope with that or does it not matter for
> some other reason?

Indeed. The textual qualification above ("whenever it is stable enough")
isn't being expressed in the code change at all.

Jan

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