Re: [PATCH] x86/centaur: Mark TSC invariant

From: Alan Cox
Date: Wed Jan 24 2018 - 13:27:03 EST


On Mon, 15 Jan 2018 09:35:45 +0800
TimGuo <timguo@xxxxxxxxxxx> wrote:

> Centaur CPU has a constant frequency TSC and that TSC does not stop in C-States.
> But because the flags are not set for that CPU, the TSC is treated as non constant
> frequency and assumed to stop in C-States, which makes it an unreliable and unusable
> clock source. Setting those flags tells the kernel that the TSC is usable, so it
> will select it over HPET. The effect of this is that reading time stamps (from kernel
> or userspace) will be faster and more efficient.

And this is true for all processors back to IDT WinChip ?

Alan