Crazy clock
Matthew Dillon
dillon at apollo.backplane.com
Mon Dec 6 08:26:16 PST 2004
On SMP boxes there is a known issue with interrupt forwarding that can
cause high latencies on clock interrupts, which would have the effect
of the clock running slower then normal (but not half speed or faster then
normal).
On UP boxes the problem ought to be fixed in HEAD unless a whole lot of
VESA calls are being made. This would be the timer 1 / timer 2 issue.
Compiling a kernel with the TIMER_USE_1 option might help here, but could
cause problems as well. However, either way we do now have code in the
kernel to detect when the BIOS munges the 8254, so 'dmesg' output after
the machine has been running for a while ought to indicate whether the
BIOS is messing with the 8254 or not.
Also, try compiling a kernel with the CLK_USE_I8254_CALIBRATION
option, do a boot -v, let the box run for a while, and post the dmesg
output.
-Matt
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