Messages in this thread |  | | Date | Sun, 11 Feb 2001 12:14:39 +0000 | Subject | Re: [OT] Major Clock Drift | From | Peter Horton <> |
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On Sun, Feb 11, 2001 at 12:06:14PM +0100, Pavel Machek wrote: > > > > > > >I've discovered that heavy use of vesafb can be a major source of clock > > > > > >drift on my system, especially if I don't specify "ypan" or "ywrap". On my > > > > > > > > > > This is extremely interesting. What version of ntp are you using? > > > > > > > > Is vesafb one of the drivers which blocks interrupts for (many) tens > > > > of milliseconds? > > > > > > Vesafb is happy to block interrupts for half a second. > > > > And has this been observed to cause clock drift? > > YEs. I've seen time running 3 times slower. Just do cat /etc/termcap > with loaded PCI bus. Yesterday I lost 20 minutes during 2 hours -- I > have been using USB (load PCI) and framebuffer. > Pavel
Is it not possible to save/check TSC in timer interrupt to correct for dropped interrupts ? (obviously only on machines that have a TSC ...)
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