Date: Mon, 10 Jun 1996 18:00:51 -0600 From: Nate Williams <nate@sri.MT.net> To: Bruce Evans <bde@zeta.org.au> Cc: current@freebsd.org, nate@sri.MT.net Subject: Re: CLOCK stuff at bootup Message-ID: <199606110000.SAA10896@rocky.sri.MT.net> In-Reply-To: <199606102355.JAA01251@godzilla.zeta.org.au> References: <199606102355.JAA01251@godzilla.zeta.org.au>
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> >CLK_USE_I8254_CALIBRATION not specified - using default frequency > >CLK_USE_I586_CALIBRATION not specified - using old calibration method > >i586 clock: 0 Hz > >CPU: Pentium (75.16-MHz 586-class CPU) > > Origin = "GenuineIntel" Id = 0x524 Stepping=4 > > Features=0x1bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8> > > >I'm assuming I'm supposed to define one or both of the above, but why? > > Because defining one or both might work better. Using sysctl to set the > actual (current) value might work better still. Umm, what am I supposed to set using sysctl? I don't remember ever seeing this kind of detail in old email. > >How do I determine which one is the more accurate, since obviously the > >i854 clock is not running at the same frequency as my Pentium chip. :) > > The i8254 clock determines long term accuracy. Run for a while and > determine the drift and/or the time daemon adjustments. How? > Use sysctl to > specify the i8254 clock frequency that minimizes the drift and/or the > adjustments or accept the default from calibration or accept the fixed > default. How? > The i586 clock determines intra-clock-interrupt times. Specify the i586 > clock frequency that minimizes the jitter in getttimeofday(). How?
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