Re: [Xen-devel] [PATCH] xen: preserve native TSC speed during migration between identical hosts

[Olaf Hering <olaf@xxxxxxxxx>]

On Wed, May 24, Konrad Rzeszutek Wilk wrote:

> Is there some form of tests that they can run to verify and test
> that this is safe? Or perhaps this is something that is based on the kernel
> versions? Like 4.11 are safe, but 3.18 is not?

I'm not sure why you are asking for specific kernel versions.


But the test is simply to boot a HVM domU with 'tsc_mode=native' and
migrate it to a similar dom0. This fails with 3.12 and 4.4 based domU
kernels, with xen-4.7 as dom0. This pretty much ruins the plan.

So far I have not investigated why the domU on the remote side does not
get any cpu time, or why it makes no progress. But in the end the I
think only a hardware upgrade to TSC-scaling capable CPUs will avoid the
performance penalty due to the TSC emulation.
I do not have access to such hardware to verify it.


Olaf

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