Concurrent Technologies RCIM, User Manual

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RCIM User’s Guide
3-6
POSIX clocks in the RCIM chain so that they are consistent, if desired, by running
rcimdate
on each slave; on return the slave’s RCIM POSIX clocks will be synchronized
with the master.
Note that this operation also synchronizes the RCIM tick clocks. Be aware that while
performing this procedure, the system time stops and time-base functions will be affected.
1. Ensure that all POSIX clocks on all RCIM slave systems are connected
using the cp command.
2. Disable the cable clock signal on the RCIM master system (using the d
command). The POSIX clocks on all systems should stop ticking.
3. Update the time values of the POSIX clocks on each system to the same
value (using the wp command).
4. Re-enable the cable clock signal on the RCIM master system (using the e
command). All clocks should begin ticking.
On RCIM systems equipped with the optional GPS module, the POSIX clock can be
synchronized to standard GPS time. Refer to the section “Using GPS for System
Timekeeping” below for information.
Automatic Synchronization
1
Each RCIM slave system can be configured so that its POSIX clock will be automatically
synchronized with that of the master on boot. To do this, uncomment either the
RCIMDATE=continuous
or
RCIMDATE=oneshot
line in
/etc/sysconfig/rcim
on the slave. Subsequently, each time the slave is booted it will run
rcimdate
either once
or continuously. If it is run once then the slave's POSIX clock will match that of the master
until such time as some application on the master executes a
clock_settime
(3) (this is
usually done by
ntp
or
ptpd
). If
rcimdate
is run in continuous mode, then the slave
will execute a
clock_settime
(3) within a few seconds of each
clock_settime
(3)
occurring on the master.
The system can also be configured to automatically synchronize the tick clocks when an
RCIM slave system is booted. This feature is disabled by default and should be used with
caution. It causes the tick clock on all systems to be reset to zero when any system in the
RCIM chain is booted, which may have an undesirable impact on processes using the tick
clock during synchronization.
To set up automatic synchronization of tick clocks when a slave system is booted, create
an empty file
/etc/sysconfig/rcim_clocksync
on the slave system. This
activates the
/etc/init.d/rcim_clocksync
startup script, asking it to reset its
RCIM board and (by default) also reset the slave RCIM boards. This uses
ssh(1)
, which
must be set up to communicate between the slave and master systems.
Using GPS for System Timekeeping
1
On RCIM systems equipped with the optional GPS module, the POSIX clock can be used
for system time synchronized to standard GPS time. A system timekeeping daemon is
utilized (e.g.
ntpd
or
chronyd
with
gpsd
) and treats the GPS receiver as a time server.