68 lines
3.5 KiB
Plaintext
68 lines
3.5 KiB
Plaintext
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README file for directory ./util of the NTP Version 3 distribution
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This directory contains the sources for the various utility programs. See
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the README and RELNOTES files in the parent directory for directions on
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how to make and install these programs.
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The ntptime.c program checks the kernel configuration for the NTP user
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interface syscalls ntp_gettime() and ntp_adjtime(). If present, the
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current timekeeping data are displayed. If not, a dissapointment is
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displayed. Do "make ntptime" in this directory to make the thing,
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but be advised that, unless you have installed the kernel support,
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there will probably be missing vital header files. See the README.kern
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file in the doc directory of this distribution for further details.
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The jitter.c program can be used to determine the timing jitter due to
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the operating system in a gettimeofday() call. For most systems the
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dominant contribution to the jitter budget is the period of the hardware
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interrupt, usually in the range 1-10 ms. For those systems with microsecond
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counters, such as recent Sun and certain Ultrix systems, the jitter is
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dominated only by the operating system.
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The timetrim.c program can be used with SGI machines to implement a
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scheme to discipline the hardware clock frequency. See the source code
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for further information.
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The byteorder.c and longsize.c programs are used during the configuration
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process to determine the byte order (little or big endian) and longword
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size (32 or 64 bits). See the ../scripts/makefile.sh script for further
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details.
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The testrs6000.c program is used for testing purposes with the IBM
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RS/6000 AIX machines. Bill Jones <jones@chpc.utexas.edu> reports:
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"I could not get a tickadj of less then 40 us to work on a RS6000.
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If you set it less then 40 us do so at your own risk!"
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The tickadj.c program can be used to read and set various kernel
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parameters affecting NTP operations. Comes now the rationale for its use.
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Then daemon's clock adjustment algorithms depend (too) strongly
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on the internals of the kernel adjtime() call, and expect it to
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match that which comes with Berkeley-flavour operating systems.
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The daemon actually reads a couple of values from your kernel
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using /dev/kmem (ugh!), the value of `tick' and the value of `tickadj'.
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`tick' is expected to be the number of microseconds which are
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added to the system time on timer interrupts when the clock isn't
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being slewed. `tickadj' is the number of microseconds which are
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added or subtracted from tick when the clock is being slewed.
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The program tickadj mimics the daemon's handling of these variables.
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If you run it (as root) and it fails or produces bizarre looking
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values you may have to torque ntp_unixclock.c in the daemon code.
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You can also use tickadj -a to set tickadj in the running kernel.
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In addition, tickadj -A will compute the value to set based on the
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kernel's value of tick, while the -t flag allows one to set the
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value of tick and the -s flag will set the value of dosynctodr
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to zero. This is an alternative for people who can't change the
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values in the kernel's disk image.
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In addition, the -p flag will set the noprintf variable. This will
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suppress any kernel messages. Kernel message can then only be seen via
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syslog(3). This inhibits clockhopping due to kernel printf's.
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The target "ntptime" can only be compiled on systems with kernel PLL
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support. This is currently only possible for SunOS4, Ultrix and DECOSF1.
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You need the propriatary header files for that. So there is no need to
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attempt to compile ntptime unless you have the above configuration.
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