Messages in this thread | | | Date | Sun, 15 Mar 2009 16:44:28 +0100 | From | Jesper Krogh <> | Subject | Re: Linux 2.6.29-rc6 |
| |
Linus Torvalds wrote: > > Jesper, here's a patch that actually tries to take teh TSC error really > into account, and which I suspect will result (on your machine) in failing > the fast PIT calibration. > > It also has a few extra printk's for debugging, and to see just what the > values are on your machine. > > The idea behind the patch is to just keep track of how big the difference > was in TSC values between two successive reads of the PIT timer. We only > really care about the difference when the MSB turns around, and we only > really care about the two end points. The maximum error in TSC estimation > will simply be the sum of the differences at those points (d1 and d2). > > We can then compare the maximum error with the actual TSC differences > between those points, and see if the max error is within 500 ppm. That > _should_ mean that it all works - assuming that the PIT itself is running > at the correct frequency, of course! > > Regardless of whether is succeeds or not, it will print out some debug > messages, which will be interesting to see.
[ 0.000000] Fast TSC delta=34227730, error=6223+6219=12442 [ 0.000000] Fast TSC calibration using PIT [ 0.000000] Detected 2312.045 MHz processor.
Using "ntpq -c peers" .. the offset steadily grows as time goes.
Full dmesg: http://krogh.cc/~jesper/dmesg-linux-2.6.29-rc8-linus1.txt
jk@quad11:~$ ntpdc -c kerninfo pll offset: 0.085167 s pll frequency: -18.722 ppm maximum error: 0.137231 s estimated error: 0.008823 s status: 0001 pll pll time constant: 6 precision: 1e-06 s frequency tolerance: 500 ppm
-- Jesper
| |