Re: [9fans] odd clock behaviour

[rog@vitanuova.com]

i just found my machine in the odd timer state again, so have
the opportunite to play with it a bit more...

presotto:
> Try setting the variable i8253dotimerset to 0 (it's now set to 1).
>	echo off > '#P'/i8253timerset

presumably i should do this at boot time, but i'd never know for sure
whether i'd nailed the problem because it presents itself so rarely.

anyway, it doesn't seem to fix much at run time.  it does change stuff
though:

% echo `{cat '#r/rtc'; cat /dev/time; }; sleep 100; echo `{cat '#r/rtc'; cat /dev/time; }
1048176273 1048211930 1048211930303113804 14857013246208 305454592
1048176320 1048212205 1048212205836287972 14941176119552 305454592
% echo `{cat '#r/rtc'; cat /dev/time; }; sleep 100; echo `{cat '#r/rtc'; cat /dev/time; }
1048176368 1048212488 1048212488976582421 15027662622720 305454592
1048176414 1048212763 1048212763054236813 15111380900864 305454592
% echo -n off > '#P'/i8253timerset
% echo `{cat '#r/rtc'; cat /dev/time; }; sleep 100; echo `{cat '#r/rtc'; cat /dev/time; }
1048176621 1048213988 1048213988275370902 15485630322688 305454592
1048176798 1048214298 1048214298823858727 15580488784384 305454592
% % echo `{cat '#r/rtc'; cat /dev/time; }; sleep 100; echo `{cat '#r/rtc'; cat /dev/time; }
1048176875 1048214418 1048214418231644733 15616962440960 305454592
1048177053 1048214695 1048214695742160153 15701729302272 305454592
%

i.e. before the change, sleep 100 was sleeping for 45 realtime seconds
for 275 seconds elapsed in /dev/time.

after changing i8253timeset, sleep 100 sleeps for 178 realtime seconds
for 277 seconds elapsed in /dev/time.

the timer was running normally when i booted the machine up.

on boot, my processor is reported as a 
996MHz GenuineIntel PentiumIII/Xeon (cpuid: AX 0x068A DX 0x383F9FF)

i had a look in my bios settings for stuff that could be influencing
the timers at runtime.

what we've got (i'm running it on AC):

	Power Mode for AC		Maximum Performance
	(which presumably chooses "Fixed Max" out of the options
	for processor speed of "Fixed Max/Medium/Slow", "Auto Medium/Slow")

	SpeedStep Technology	Automatic
	(which says it's "Maximum Performance" on AC, i.e. always at high speed)

	CPU power management	Automatic
	(says: "enables or disables the power saving feature that stops
	the microprocessor clock automatically when there are no system
	activities.")

the last one seems like a possible culprit, i guess.