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<TITLE>Solaris hints and kinks</title><link href="scripts/style.css" type="text/css" rel="stylesheet">
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Information on compiling and executing ntpd under Solaris.
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Last Updated: Sun Jun 21 01:32:18 EDT 1998,
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<! -- This is deliberately not a mailto -- > <jhawk@MIT.EDU>
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If you're not running Solaris 2.5.1 or later, it is likely
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that you will have problems; upgrading would be a really good plan.
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<H3>All Solaris versions</H3>
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We have a report that says starting with Solaris 2.6 we should leave
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<I>dosynctodr</I> alone.
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<A HREF="solaris-dosynctodr.html">Here is the report</A>.
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Proper operation of ntp under Solaris may require setting the kernel
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variable <I>dosynctodr</I> to zero (meaning "do not synchronize the clock
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to the hardware time-of-day clock"). This can be done with the
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If you prefer, it can also be done with the native Solaris kernel debugger:
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echo dosynctodr/W0 | adb -k -w /dev/ksyms /dev/mem
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Or, it can also be set by adding a line to /etc/system:
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Instead of the <I>tick</I> kernel variable, which many operating
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systems use to control microseconds added to the system time every
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clock tick (c.f. <A HREF="../../notes.html#frequency_tolerance">Dealing
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with Frequency Tolerance Violations</A>), Solaris has the variables
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<I>nsec_per_tick</I> and <I>usec_per_tick</I>.
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<I>nsec_per_tick</I> and <I>usec_per_tick</I> control the number of
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nanoseconds and microseconds, respectively, added to the system clock
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each clock interrupt. Enterprising souls may set these based on
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information collected by ntpd in the <CODE>/etc/ntp.drift</CODE> file
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to correct for individual hardware variations.
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On UltraSPARC systems, <I>nsec_per_tick</I> and <I>usec_per_tick</I>
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are ignored in favor of the <I>cpu_tick_freq</I> variable, which
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should be automatically be determined by the PROM in an accurate
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In general, the same ntp binaries should not be used across multiple
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operating system releases. There is enough variation in the core operating
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system support for timekeeping that a rebuild of ntpd for the idiosyncracies
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of your specific operating system version is advisable.
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It is recommended that ntp be started via a script like <A
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HREF="solaris.xtra.S99ntpd">this one</A>, installed in
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<CODE>/etc/init.d/ntpd</CODE> with a symbol link from
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<CODE>/etc/rc2.d/S99ntpd</CODE>.
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Solaris 2.6 adds support for kernel PLL timekeeping, but breaks this
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support in such a fashion that using it worse than not. This is <A
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HREF="solaris.xtra.4095849"> SUN Bug ID 4095849</A>, and it is not yet
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fixed as of June 1998.
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<H3>Solaris 2.5 and 2.5.1</H3>
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On UltraSPARC systems, calculation of <I>cpu_tick_freq</I> is broken
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such that values that are off by significant amounts may be used
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instead. This unfortunately means that ntpd may have severe problems
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keeping synchronization. This is <A HREF="solaris.xtra.4023118"> SUN Bug ID
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4023118</A>. Bryan Cantrill <! -- <bmc@eng.sun.com> --> of Sun
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posted <A HREF="solaris.xtra.patchfreq">patchfreq</A>, a workaround script,
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to comp.protocols.time.ntp in March of 1997.
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<STRONG>I can't vouch for the accuracy the information below this
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rule. It may be significantly dated or incorrect.</STRONG>
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Solaris 2.2 and later contain completely re-written clock code to
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provide high resolution microsecond timers. A benefit of the
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re-written clock code is that adjtime does not round off its
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adjustments, so ntp does not have to compensate for this
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rounding. Under Solaris 2.2 and later, ntp #define's
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<CODE>ADJTIME_IS_ACCURATE</CODE>, and does not look for the <I>tickadj</I>
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(This originally written by William L. Jones <jones@chpc.utexas.edu>)
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Solaris 2.1 contains fairly traditional clock code, with <I>tick</I>
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Since settimeofday under Solaris 2.1 only sets the seconds part of timeval
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care must be used in starting xntpd. I suggest the following start
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<BR>ntpdate -v server1 server2
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<BR>ntpdate -v server1 server2
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The first tickadj turns of the time of day clock and sets the tick
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adjust value to 1 millisecond. This will insure that an adjtime value
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of at most 2 seconds will complete in 20 seconds.
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The first ntpdate will set the time to within two seconds
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using settimeofday or it will adjust time using adjtime.
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The first sleep insures the adjtime has completed for the first ntpdate.
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The second ntpdate will use adjtime to set the time of day since the
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clock should be within 2 seconds of the correct time.
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The second tickadj set the tick adjust system value to 5 microseconds.
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The second sleeps insure that adjtime will complete before starting
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I tried running with a tickadj of 5 microseconds with out much success.
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200 microseconds seems to work well.
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Prior versions of this file had major text contributed by:
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<LI>Denny Gentry <denny@eng.sun.com>
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