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Date: Sun, 11 Feb 2001 12:06:14 +0100
From: Pavel Machek <pavel@suse.cz>
To: Andrew Morton <andrewm@uow.edu.au>
Cc: Hacksaw <hacksaw@hacksaw.org>,
        Tom Eastep <teastep@seattlefirewall.dyndns.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [OT] Major Clock Drift
Message-ID: <20010211120614.E23048@atrey.karlin.mff.cuni.cz>
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Hi!

> > > > >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
-- 
The best software in life is free (not shareware)!		Pavel
GCM d? s-: !g p?:+ au- a--@ w+ v- C++@ UL+++ L++ N++ E++ W--- M- Y- R+
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