Date: Tue, 12 Nov 2002 10:21:54 -0600 From: "Dr. Michael Mackey" <mackey@engineering.uiowa.edu> To: John Baldwin <jhb@FreeBSD.org>, freebsd-alpha@FreeBSD.org Subject: Re: Extreme time drift in SMP mode Message-ID: <3DD12AA2.8D84B3E2@engineering.uiowa.edu> References: <XFMail.20021112104816.jhb@FreeBSD.org>
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You're right, the clock on the Lynx (2100a) is an 8254:
(from the output of dmesg)
FreeBSD 5.0-CURRENT #0: Mon Nov 11 15:31:50 CST 2002
mackey@home.:/usr/src/sys/alpha/compile/HOME
Preloaded elf kernel "/boot/kernel/kernel" at 0xfffffc00006c2000.
DEC AlphaServer 2100A
AlphaServer 2100A 5/300, 291MHz
8192 byte page size, 2 processors.
CPU: EV5 (21164) major=5 minor=5
OSF PAL rev: 0x4000100020116
real memory = 199155712 (189 MB)
avail memory = 187490304 (178 MB)
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
--- snip ---
Timecounters tick every 0.976 msec
Timecounter "i8254" frequency 1193182 Hz
--- snip ---
John Baldwin wrote:
>
> On 11-Nov-2002 Andrew Gallatin wrote:
> >
> > Michael A. Mackey writes:
> > > It takes precisely twice as long (20 seconds) to run `sleep 10`.
> > >
> > > Why can't ntpd keep things in line?
> > >
> >
> > Because its not desgined to fix a clock which is that broken -- it
> > only increments a second or so at a time. Far too slow for your
> > purposes.
>
> So the clock is running at half-speed now? Hmm, the 2100[A] are
> Tincup, not Turbolaser, right? So it should be using the i8254 for
> its timecounter. Maybe the 8254 timecounter isn't setup right on
> the 2100a?
>
> --
>
> John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
> "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
--
Prof. Michael A. Mackey (michael-mackey@uiowa.edu)
Biomedical Engineering / Radiology
University of Iowa, Iowa City, Iowa
Voice: 319-335-6058 Fax: 319-335-5631
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