Re: [PATCH] x86: set_cyc2ns_scale() remove tsc_now and ns_now

[Ingo Molnar <mingo@elte.hu>]

* Andi Kleen <andi@firstfloor.org> wrote:

> (actually it is still the wrong time -- really needs a grace period 
> during which the TSC is not used 
> ftp://firstfloor.org/pub/ak/quilt/patches/sched-clock implemented some 
> of these ideas against an older kernel)

recent CPUs have constant-freq TSCs so it's mostly a legacy issue, but 
the affected installed base is still significant to warrant a fix.

we dont really have to worry about complications like grace periods - 
higher layers in the scheduler protect against temporary sched_clock() 
outliers. So i think this can all be done much simpler. Just get rid of 
the global cpu_khz notion, sched_clock() should simply follow the ->freq 
value - and that's it.

	Ingo