Time precision, adjtime(x) vs. gettimeofday

Ethan Benson erbenson at alaska.net
Fri Oct 10 17:53:03 EST 2003

On Fri, Oct 10, 2003 at 01:12:54AM -0400, Bill Fink wrote:
> This discussion prompted me to finally ask about another clock related
> problem I see on the 867 MHz G4 systems at work. The clocks on
> these systems continuously run 0.2% slow (about 3 minutes per day).
> Apparently this is more than ntp can adjust for (using scaling), as I
> get many of these error messages in the log:

is it a quicksilver G4?  i maintain one of those and its time goes off
much faster then that (3 minutes within a couple hours).

the fix is rather simple:

--- linux.old/arch/ppc/platforms/pmac_time.c.orig	Sat Nov 30 02:33:49 2002
+++ linux/arch/ppc/platforms/pmac_time.c	Sat Nov 30 02:33:22 2002
@@ -262,7 +262,9 @@
 	 * calibration. That's better since the VIA itself seems
 	 * to be slightly off. --BenH
+#if 0
 	if (!machine_is_compatible("MacRISC2"))
 		if (via_calibrate_decr())

in the case of the quicksilver VIA is FAR better then whatever it uses

Ethan Benson

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