Re: tip.today - scheduler bam boom crash (cpu hotplug)

Thomas Gleixner
2017-02-27T18:06:14Z

On Mon, 27 Feb 2017, Paolo Bonzini wrote:
> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> index 2724dc82f992..3080b6877190 100644
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -1398,6 +1398,9 @@ void __init tsc_init(void)
>
> use_tsc_delay();
>
> + if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
> + mark_tsc_unstable("not invariant");

Errm, no.

That makes TSC unusable for systems which do not go into C/P states in
which the TSC stops. There is a world outside KVM ....

Thanks,

tglx