David J Taylor wrote:
Richard B. Gilbert wrote:
[]
WinDoze exhibits the same problem with lost clock interrupts. The
difference is that there is nothing you can do about WinDoze except
run a better O/S! The problem results from interrupts being masked or
disabled for two or more consecutive clock "ticks". Only the first
"tick" registers, the rest are lost. This typically happens during
heavy disk activity. Runing the multi-media timers can also gum
things up royally but there is a fix or workaround for that. If your
clock gains rather than loses time, you needn't worry about lost
interrupts. If the machine drifts badly when idle, the problem is
probably not lost interrupts.
What is your evidence for saying this about lost interrupts with Windows?
I ask because I have Windows running NTP on a number of systems ranging
from an old 266MHz AMD running Windows NT4 up to a 2.8GHz Pentium 4
running Windows 2000, and a 1.9GHz Pentium 4 running Windows XP, and I
have not seen problems with lost interrupts. Of course, disk DMA should
be enabled, and I suppose that a badly written third-party device driver
could cause problems. What situations might cause lost interrupts, and
how can they be avoided? Do you think these problems are present in the
basic OS?
You are, of course, correct that the multi-media timers do need to be
permanently enabled (if you run software which might enable and disable
them), and fortunately there is now a version of NTP which does that:
http://www.meinberg.de/english/sw/ntp.htm
David
My words were based on what I've read here. I do not run ntpd on
Windoze. Based on about twelve years as a Windoze user from 3.1 to XP,
I think it's fair to say that Windoze is badly written. It has gotten
better over the years but it's still far from what I'd call reliable,
well designed, or well executed. My Unix and VMS systems stay up as
long as the power stays on (I've had a VMS system with over two years of
continuous up time); my Windows systems have to rebooted after a week to
ten days of use (it used to be daily, or more)!
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