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

From: Christoph Lameter
Date: Tue Sep 07 2004 - 16:04:01 EST


On Tue, 7 Sep 2004, George Anzinger wrote:

> Also, we don't "know" what rate the TSC is actully 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 retrive that information. Doesnt the BIOS on
i386 allow you to get to that information?

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