Re: do_gettimeofday vs. rdtsc in the scheduler

[Andi Kleen]

On Tue, Sep 17, 2002 at 04:32:46PM -0700, David S. Miller wrote:
>    From: john stultz <[e-mail]>
>    Date: 17 Sep 2002 16:32:15 -0700
>    
>    Additionally, where is this system tick thing? You make it sound like
>    its a register in the cpu, and while the Ultra-III may have one, I'm
>    unaware of a system/bus tick register on intel chips. Is it in some
>    semi-documented MSR?
> 
> It's in a register on Ultra-III.  The whole point of this
> conversation, if you read my initial postings, is that
> "this should have been specified in the x86 architecture"
> 
> I know full well it isn't currently :-)

Sorry, it's wrong. The x86 architecture has several such registers
(apic timers, 8253 timer, HPET [Microsoft requires this for new 
hardware that will be w*s certified]) 
They just all suck on various systems or in general. HPET is ok, 
but still not widespread enough.

-Andi