Date: Sat, 14 Feb 2015 11:17:03 -0800 From: Rick Thomas <rbthomas@pobox.com> To: Adam Vande More <amvandemore@gmail.com> Cc: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: How to adjust clock frequency in FreeBSD 10.1 ? Message-ID: <2F352B9F-A1CA-47D3-B17D-4C7918B80636@pobox.com> In-Reply-To: <CA%2BtpaK1rJszT2-JMUqBp6hb3nMDVQchn8FBR7icQaSNi1gad4w@mail.gmail.com> References: <AE5A370C-A7F7-41D2-900D-B26521A2D705@pobox.com> <CA%2BtpaK3bn-UPrqTU9cME2V9Ls=auf1n0rdr%2BuHA1b7pcspmiPw@mail.gmail.com> <BF8DFE66-E19D-45DA-A0C3-EB08D7E9DFF9@pobox.com> <CA%2BtpaK1rJszT2-JMUqBp6hb3nMDVQchn8FBR7icQaSNi1gad4w@mail.gmail.com>
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On Feb 14, 2015, at 4:50 AM, Adam Vande More <amvandemore@gmail.com> wrote: > On Sat, Feb 14, 2015 at 5:42 AM, Rick Thomas <rbthomas@pobox.com> wrote: > >> When I try to change the frequency with (e.g.) >> sysctl kern.timecounter.tc.timebase.frequency=36000000 >> >> I get >> sysctl: oid ‘kern.timecounter.tc.timebase.frequency' is read only >> > > Yeah, pretty clear that sysctl isn't going to help you in any way in "man 4 > timecounters" > > Is there some other way to set the frequency? >> > > Sure, but I thought keeping accurate time was the goal? If so, sharing the > output from the first command I gave you is a good start. Ooops… Sorry! I thought I had already done that. In any case, here it is: > [root@grey ~]# sysctl kern.timecounter > kern.timecounter.fast_gettime: 1 > kern.timecounter.tick: 1 > kern.timecounter.choice: timebase(0) dummy(-1000000) > kern.timecounter.hardware: timebase > kern.timecounter.alloweddeviation: 5 > kern.timecounter.stepwarnings: 0 > kern.timecounter.tc.timebase.mask: 4294967295 > kern.timecounter.tc.timebase.counter: 1981288884 > kern.timecounter.tc.timebase.frequency: 33290001 > kern.timecounter.tc.timebase.quality: 0 > [root@grey ~]# I’m guessing that by tuning the timebase.frequency number, I can make the clock run effectively slower or faster. If I find the right value, I can correct the problem I’m seeing with ntpd. In case it matters, this is a powerpc Macintosh G4, so the only available timecounter is “timebase”. Switching to a different timecounter is not an available option. Rick
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