[ntp:questions] Re: Is ntp really what I need?

Richard B. Gilbert rgilbert88 at comcast.net
Mon Feb 14 20:54:47 UTC 2005

Paul Hilton wrote:

>On Mon, 14 Feb 2005 11:48:05 -0500, Richard B. Gilbert wrote:
>>I'm afraid you are right about your system losing clock interrupts.  
>>Unfortunately ntpd must rely on the proper operation of the clock.  It 
>>can correct minor errors but it can do nothing in the face of an O/S 
>>that gives higher priority to playing videos than to updating the 
>>clock.  Change to a better O/S or play your videos somewhere else.
>The timer interrupt is on IRQ0, theoretically higher priority than any
>other. Playing videos is just an example, any job that uses all available
>resources ( maybe interrupts, or maybe processor time ) causes the same
>problem, but to a much lesser extent. Why it is losing the interrupts I
>don't know. O/S decisions can obviously be changed or reconfigured if one
>really knows what the problem is. This is my desktop machine, where I
>sometimes play videos. It seems possible that kernel 2.6.x may do better,
>I found a load of discussion about timer tick interrupts implying that
>things were improved in the 2.5 series. Changing O/S for the rare
>occasions when the clock goes astray seems a bit drastic though, what
>would you suggest?
>Thanks for the reply,
>Paul Hilton
IRQ priority is not the issue!   Code that disables or masks interrupts 
for extended periods is the usual cause of this sort of thing.  Linux 
and Windoze are both noted for this behavior.

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