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Date:      Sat, 13 Apr 2002 15:50:10 +0200 (SAT)
From:      John Hay <jhay@icomtek.csir.co.za>
To:        hackers@freebsd.org
Subject:   microtime trustworthiness during booting?
Message-ID:  <200204131350.g3DDoBn69302@zibbi.icomtek.csir.co.za>

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Hi,

From what stage during the boot process can I trust that microtime() will
give me incrementing time?

The reason I ask is that I see microtime() jump backwards consistently
during the ich_calibrate() function in the ich sound driver. The values
look basically the same every time. Something like this:

t1 2 sec 389291 usec
t2 0 sec 32061 usec

The interesting thing is that on another identical machine it doesn't
happen and the calibrate routine works correctly. The only difference
is that that machine use a GENERIC kernel and mine have a kernel with
apm removed so that I can use the TSC as timecounter.

Can it be that there is some kind of glitch somewhere when the TSC
take over as timecounter?

John
-- 
John Hay -- John.Hay@icomtek.csir.co.za / jhay@FreeBSD.org

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