Re: [PATCH v1] watchdog: Use a reference cycle counter to avoid scaling issues

From: Andi Kleen
Date: Fri Apr 24 2015 - 05:59:11 EST

> There are better ways to do that than using heuristics. We have to
> deal with 3 variants of the reference counter:
> 1) Core and Atom: counts bus cycles and we know that frequency already
> from the local apic calibration
> 2) Nehalem, Westmere: Same as TSC
> 3) Sandybridge and later: XCLK which is 100MHz
> No magic calibration, just use the information which we have on our
> hands already.

This is a really bad idea. We basically would need to maintain a big
switch with model numbers, with new cases added for every new CPU.
Would be a maintenance nightmare.


ak@xxxxxxxxxxxxxxx -- Speaking for myself only
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