Timedirft between system clock and hwclock

[Henry Ritzlmayr]

Am Donnerstag, den 10.05.2007, 15:52 +0200 schrieb Henry Ritzlmayr:
> Am Donnerstag, den 10.05.2007, 10:06 -0300 schrieb John DeDourek:
> > Henry Ritzlmayr wrote:
> > > ... kernel: Your time source seems to be instable or 
> > 
> > > some driver is hogging interupts
> > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > This would be my first guess.  The timer mechanism stores only one pending
> > interrupt.  Thus, if the clock interrupt occurs twice while some driver has
> > interrupts locked out, you typically get only one increment of time and the
> > system time, which is just the sum of the increments falls behind.
> > 
> > This is made worse by the current standard kernels which have upped the
> > clock rate from 100 interrupts per second to 250 or more.  At 100 interrupts
> > per second, a device driver needs to lock out interrupts for 10 ms. before a
> > timer tick is lost.  At 1000 interrupts per second, any driver that locks
> > out interrupts for more than 1ms will cause a timer interrupt loss.
<snip>

Final findings and solution:

Mainboard: ASUS P5B-VM DO

Problem with lost ticks exists with any Kernel from FC6 (up to this
date), while module e1000 is loaded an link speed is at 1000Mb/s.

Reducing the link speed to 100Mb/s leads in to less lost ticks but they
are still there. 

I got rid of all lost ticks by enabling AMT within the BIOS and
disabling the LAN Controller! Obviously even AMT is disabled (by
default) there is still something hogging the interrupts. After
disabling the LAN Controller, AMT can be disabled for good now. 

Hint: When the AMT-Menu is called first time, the default password has
to be changed. The Rules for the new password are:

At least 8 characters long
Includes at least one number character (0-9)
Includes at least one non-alphanumeric ASCII character (such as !,&, %)
Contains both upper- and lowercase Latin characters, or non-ASCII
characters (UTF+00800 and above)

Henry