Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt

["Maciej W. Rozycki" <macro@linux-mips.org>]

On Wed, 13 Jul 2005, Benjamin LaHaise wrote:

> That's one thing I truely dislike about the current timer code.  If we 
> could program the RTC interrupt to come into the system as an NMI (iirc 
> oprofile already has code to do this), we could get much better TSC 
> interpolation since we would be sampling the TSC at a much smaller, less 
> variable offset, which can only be a good thing.

 And we'd get a lot more crashes on broken systems that do not handle NMIs 
in the SMM -- this is the very reason the NMI watchdog is disabled these 
days by default.  A whole lot of systems simply cannot handle NMIs 
happening randomly.

 Programming an I/O APIC to deliver the RTC interrupt (or any other that's 
edge-triggered) as an NMI is itself trivial (we can do this for the PIT 
for the NMI watchdog already).

  Maciej
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