Re: Timestamp counters on SMP

From: Vojtech Pavlik (vojtech@suse.cz)
Date: Fri Mar 31 2000 - 17:53:33 EST


On Fri, Mar 31, 2000 at 02:46:10PM -0800, H. Peter Anvin wrote:

> It's probably impossible to detect; we probably should provide a no-tsc
> kernel flag though.

It should be possible to detect by comparing the TSC value to jiffies or
RTC now and then. If it diverges, then there is a problem. This would
also catch the two-different-cpus-smp case. Not at boot time, but while
running.

> The no-tsc flag should clear the tsc bit in the capabilities, and also
> set the bit in CR4 that disables access to it from user space.

I doubt this would help, because drivers are already making their
decision on CONFIG_TSC ...

-- 
Vojtech Pavlik
SuSE Labs

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