Messages in this thread | | | Date | Mon, 9 Mar 2009 21:26:48 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: Linux 2.6.29-rc6 |
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On Mon, 9 Mar 2009, Jesper Krogh wrote: > > First boot. > [ 0.000000] ref_freq: 2311825 pit_freq: 2310386 > Second boot: > [ 0.000000] ref_freq: 2311803 pit_freq: 2310190 > Third boot: > [ 0.000000] ref_freq: 2311824 pit_freq: 2310080 > Fourth boot: > [ 0.000000] ref_freq: 2311831 pit_freq: 2310130
It's really quite impressively stable, but the fast-PIT calibration frequency is reliably about 3/4 of a promille low. Or, put another way, the TSC difference over the pit calibration is just a _tad_ too small compared to the value we'd expect if that loop of pit_expect_msb() would really run at the expected delay of a 1.193182MHz clock divided by 256.
And it's stable in that it really always seems to be off by a very similar amount. It's not moving around very much.
I also wonder why it seems to happen mainly just to _you_. There's absolutely nothing odd in your system, neither a slow CPU or anything else that would stand out.
Grr. Very annoyingly non-obvious.
Linus
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