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	Fri, 21 Aug 1998 11:40:39 +1000
Date: Fri, 21 Aug 1998 11:40:39 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199808210140.LAA11972@godzilla.zeta.org.au>
To: brian@Awfulhak.org, green@unixhelp.org
Subject: Re: 13 months of user time?
Cc: bde@zeta.org.au, freebsd-current@FreeBSD.ORG, jwd@unx.sas.com,
        phk@critter.freebsd.dk, tlambert@primenet.com
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>In /sys/i386/isa/clock.c, should i8254_offset be reset after it's 
>added to ``count'' ?  What happens when i8254_offset wraps ?  Might 
>this be the problem ?  Would it only be a problem for machines that 
>have an irregular clock heart-beat, sometimes allowing loads of calls 
>to i8254_get_timecount() before clkintr() happens ??

The problem is very unlikely to be with i8254_get_timecount().  Bugs
would probably make it jump forward.

>I reckon a diagnostic in microuptime() that compares the value 
>assigned to *tv with the previous value and moans if they decrease 
>may prove informative.... and maybe a similar thing in 
>i8254_get_timecount() - the machine I was having problems with was 
>running apm, so it used the i8254 timecounter rather than the tsc 
>counter.

The problem is quite likely to be with apm.  It does bad things to
reinitialize the time.  Damage is limited by not reinitializing the
time unless apm has apparently been asleep for > 2 seconds (or < -2
seconds :-).

Bruce

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