[ntp:questions] Re: IEEE 1588 support in NTP?

Martin Burnicki martin.burnicki at meinberg.de
Thu Nov 3 10:26:43 UTC 2005


Richard,

Richard B. Gilbert wrote:
> Linux has been known to have timekeeping problems due to losing clock
> interrupts.   Each lost interrupt can introduce an error of  one or ten
> milliseconds.  If the kernel parameter HZ is set to 1000, the clock
> ticks 1000 time a second and the system is likeliest to lose
> interrupts.  It works much better if HZ is set to 100.

Lost timer ticks are not a specific Linux problem. As already mentioned in
another thread, I know that at least Windows, Novell NetWare and OS/2 have
had problems with IDE disk drivers which had disabled interrupts for too
long. 

In all of these cases this has been related to specific versions of the IDE
driver shipped with a specific version of the OS, and drivers have been
made available where this has been fixed. 

Of course, if you increase the interrupt rate then the chance interrupts are
lost is higher than with a lower rate, if a driver disables interrupts for
a specified time interval.


Martin
-- 
Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont
Germany




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