Re: [Xen-devel] [PATCH v11] tolerate jitter in cpu_khz calculation to avoid TSC emulation

[Olaf Hering <olaf@xxxxxxxxx>]

Am Thu, 13 Dec 2018 07:46:36 -0700
schrieb "Jan Beulich" <JBeulich@xxxxxxxx>:

> >>> On 13.12.18 at 14:25, <olaf@xxxxxxxxx> wrote:  
> > The question is, how much drift can be tolerated even without my patch.  
> This depends on what a system is used for. A few seconds off may
> be fine for one purpose, but a significant problem for another.
> Similarly a sudden (however small) change to the TSC tick rate
> may be a problem for one purpose, but not for another.

Sure it depends on the usage. Should the default favor the "common" case
for domUs that are aware of a drift when using TSC and therefore use NTP,
or should the default favor the other case of domUs that, intentionally
or not, rely on emulation to reduce the expected drift?

And if this has to become a knob, then v10 might be the way to go.

Olaf

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