Date: Mon, 10 Jun 1996 19:18:12 -0600 From: Nate Williams <nate@sri.MT.net> To: Bruce Evans <bde@zeta.org.au> Cc: nate@sri.MT.net, current@freebsd.org Subject: Re: CLOCK stuff at bootup Message-ID: <199606110118.TAA11261@rocky.sri.MT.net> In-Reply-To: <199606110018.KAA02186@godzilla.zeta.org.au> References: <199606110018.KAA02186@godzilla.zeta.org.au>
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> >> 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. > > Clock nominal frequencies. > > >> The i8254 clock determines long term accuracy. Run for a while and > >> determine the drift and/or the time daemon adjustments. > > >How? > > Compare the output of `date` with an accurate clock or look in the time > deaemon log files. And how would I do that? I'm not sure what kind of 'drift' I'm expecting. (Forgive me, but I'm not clock expert, nor do I understand what all of this buys me if I have to hand-set all of these variables.) If I have to hand-set everything and play with this on a per-machine basis, then it's not worth it. What does having all of this flexibility buy me? > >> Use sysctl to > >> specify the i8254 clock frequency that minimizes the drift and/or the > > >How? > > Look in the output of `sysctl -a` to find the relevant variable and set > it as usual. machdep.i8254_freq: 1193182 This was set at bootup time already, so how do I determine what to set it to except via trial and error. > > >> The i586 clock determines intra-clock-interrupt times. Specify the i586 > >> clock frequency that minimizes the jitter in getttimeofday(). > > >How? > > First find the frequency. Set it as above. machdep.i586_freq: 0 Set it to the stuff that was kicked out by the kernel? Why isn't aren't these values already set by default? Nate
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