[ntp:questions] Re: linux system clock egregiously slow!

David Wuertele dave at rokulabs.com
Thu Jan 22 19:11:00 UTC 2004


Hal> (At least) One of us can't do math.
Hal> You are expecting 150.0  You get 149.6

Actually, I had been under the impression that I was expecting closer
to 149.6MHz for the PCC.  Computing the actual PCC frequency is
actually quite difficult, there are a lot of registers that get set by
the BIOS that are not very well documented.  But after consulting One
Who Knows, I learned that we really are operating at 300MHz, plus or
minus 30PPM.  So my mips_counter_frequency really is off by 2637 PPM.

What I also learned was that our 27MHz RTC timers and our PCC are
running off the exact same crystal.  That is interesting, because it
means I should expect ZERO deviation between the PCC and the MIPS
frequency.  The fact that I see 2637 PPM is a pretty bad systematic
error!!!



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