Date: Tue, 8 Apr 2014 10:41:44 -0400 From: John Baldwin <jhb@freebsd.org> To: Alexey Dokuchaev <danfe@nsu.ru> Cc: freebsd-ppc@freebsd.org Subject: Re: System clock falls behind quickly on Mac mini G4 Message-ID: <201404081041.44272.jhb@freebsd.org> In-Reply-To: <20140408142929.GC39088@regency.nsu.ru> References: <20140328071714.GA45961@regency.nsu.ru> <201404071704.58659.john@baldwin.cx> <20140408142929.GC39088@regency.nsu.ru>
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On Tuesday, April 08, 2014 10:29:29 am Alexey Dokuchaev wrote: > On Mon, Apr 07, 2014 at 05:04:58PM -0400, John Baldwin wrote: > > Also, if the frequency is calibrated incorrectly during boot for some reason, > > your time-of-day clock will drift constantly. I've seen this on x86 boxes > > Yes, I remember a thread (x86ish) some time ago about bogus TSC calibration, > but... > > > where the TSC was calibrated incorrectly due to an interaction with SMM > > interrupts for legacy USB emulation. In that case, adjusting machdep.tsc_freq > > to match the frequency from the CPU's brand string "fixed" the drift. > > ... sysctl -a does not show machdep.tsc_freq for me on this G4 box for > some reason (GENERIC kernel). It wouldn't be tsc_freq on a powerpc box. You'd need to see what your timecounter is and what frequency it is using (kern.timecounter nodes) and see if that is adjustable. -- John Baldwin
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