Re: [RFC] New Time of day proposal (updated 9/2/04)

[George Anzinger]

Christoph Lameter wrote:
> On Tue, 7 Sep 2004, George Anzinger wrote:
>
>
> > Also, we don't "know" what rate the TSC is actually clocking so we must
> > "discover" it at boot time.  This process either is inaccurate or slow (I think
> > we use ~ 50 ms these days which gives an error of ~10 TSC cycles on a 800MHZ
> > box).  FWIW the problem here is the sync up with the I/O backplane to find the
> > start and ending of the measured time.
> >
> > I suspect that the IA64 "tells" you what its clock rate is.  Right?
>
>
> Not the CPU itself. There is a special hardware I/O interface called the
> PAL/SAL that allows one to retrieve that information. Doesn't the BIOS on
> i386 allow you to get to that information?

Not as far as I know.  If it did we would kick out the calibrate loop and boot 
some 50ms faster (always a good thing).  Could be somebody else has better info 
here...

--
George Anzinger   george@xxxxxxxxxx
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml

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