On 04-Feb-02 John Polstra wrote: > 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.
X is hardclock I think, since hardclock() calls tc_windup(). I'm not sure what Y is except that it is indeed a known value. phk should know as he is Mr. Timecounter. > John > -- > John Polstra > John D. Polstra & Co., Inc. Seattle, Washington USA > "Disappointment is a good sign of basic intelligence." -- Chögyam Trungpa -- John Baldwin <[EMAIL PROTECTED]> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
