In article <[EMAIL PROTECTED]>,
Dominic Marks  <[EMAIL PROTECTED]> wrote:
> On Mon, Feb 04, 2002 at 01:21:25PM -0800, John Polstra wrote:
> > I'm trying to understand the timecounter code, and in particular the
> > reason for the "microuptime went backwards" messages which I see on
> > just about every machine I have, whether running -stable or -current.
> 
> I see them everywhere with -CURRENT, but not at all with -STABLE. This is
> with two seperate machines. Perhaps that may add clues.

I'm looking for something less empirical than that.  When somebody
says this problem is caused by too much interrupt latency, I assume
they have a mental model of what is going wrong when this excessive
latency occurs.  Given that, it should be possible to make a statement
like, "If X is never locked out for longer than Y, this problem
cannot happen."  I'm looking for definitions of X and Y.  X might be
hardclock() or softclock() or non-interrupt kernel processing.  Y
would be some measure of time, probably a function of HZ and/or the
timecounter frequency.

John
-- 
  John Polstra
  John D. Polstra & Co., Inc.                        Seattle, Washington USA
  "Disappointment is a good sign of basic intelligence."  -- Chögyam Trungpa


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