Running without clock interrupts?

John Giacomoni john.giacomoni at
Thu Jan 10 19:40:11 PST 2008

I'd like to run a long loop with a minimum of interrupts, specifically  
without any scheduler or timer interrupts, the introduced jitter is  
Is this possible in FreeBSD 7?   If so how should I proceed? I can  
take as long as I need after the loop has completed to restore/ 
reinitialize any necessary state.

I do want to be able to process other interrupts to handle page faults  
and the like.

I'm working on dual core dual processor amd opteron setups right now  
and would like to support the intel family processors as well.

It seems that what I want to do is to disable/mask acpi timer  
interrupts for the processor but trying to read the 0xfee00320  
register (lvt_timer) causes a panic.
Alternatively, I could hook in the timer handler to return immediately  
when a flag is set, though this still might introduce more jitter than  
I'd like.


John Giacomoni


John.Giacomoni at
University of Colorado at Boulder
Department of Computer Science
Engineering Center, ECCR 1B50
430 UCB
Boulder, CO 80303-0430

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