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Date:      Sun, 05 Apr 1998 14:14:37 +0200
From:      Poul-Henning Kamp <phk@critter.freebsd.dk>
To:        Bruce Evans <bde@zeta.org.au>
Cc:        peter@netplex.com.au, smp@FreeBSD.ORG
Subject:   Re: more SMP stuff 
Message-ID:  <7433.891778477@critter.freebsd.dk>
In-Reply-To: Your message of "Sun, 05 Apr 1998 22:09:39 %2B1000." <199804051209.WAA03352@godzilla.zeta.org.au> 

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In message <199804051209.WAA03352@godzilla.zeta.org.au>, Bruce Evans writes:
>>>I found the bug in microtime():
>>>(1) the dummy timecounter has a frequency of only 10^5 Hz, but it runs
>>>    much faster than that so we get too-large delta counts.
>>
>>Ups, I intended that to be 10^6 Hz...
>
>The scaling needs to be more robust since the h/w counter might be
>slower than 10^6 hz.

No, that is a design decision.  Timecounter must be >= 1MHz.

>>This isn't it anyway, the dummy counter is only used by syscons 
>>screensaver calls to getmicroruntime();
>
>It's used by my version of the floppy driver which calls microtime()
>to timestamp certain events.

before the i8254 is initialized ?

>I don't think I call nanotime() so early.  My rtcintr() calls
>nanotime() to gather statistics, and nanotime() was reentered.
>I don't see any reentrancy problems.  There will be one when
>nanotime updates tc->nanotime like it should.

No it shouldn't, I'm sorry but I cannot find a way where that makes
fewer problems than it fixes...

--
Poul-Henning Kamp             FreeBSD coreteam member
phk@FreeBSD.ORG               "Real hackers run -current on their laptop."
"Drink MONO-tonic, it goes down but it will NEVER come back up!"

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