Re: 2.6.35-rc1 regression with pvclock and smp guests

Michael Tokarev
2010-10-03T08:27:18Z

03.10.2010 03:42, Zachary Amsden wrote:
[]
> Umm... do you guys have this commit? This is supposed to address the
> issue where the guest keeps resetting the TSC. A guest which does that
> will break kvmclock. It only happens on SMP, and it's much worse on AMD
> CPUs...
>
> sound like your scenario.

I'm using 2.6.35.y kernel.org kernel which does not have this patch.
I discovered this problem with this kernel first, and later it become
apparent that it is present in 2.6.32 stable series as well -- that's
my current main target, 2.6.35 for testing stuff and 2.6.32 for a
backport later.

> commit bd59fc8ff95126f27b7a0df1b6cc602aa428812d

And it does not apply to 2.6.35 too, -- there's no kvm_write_tsc()
function in arch/x86/kvm/x86.c, and no code similar to that.

I browsed Linus git history, and see that this is a part of
larger patch series, which were already mentioned in this
thread several times, but without any mention of the base
it should be applied to (you mentioned another of your
patches in this series, the one that writes zero to tsc
somewhere, and told it wont apply but just shows the bug).

Should I try to apply whole thing to 2.6.35?

Thanks!

/mjt