Installation guide

G.8.6.1 ULTRIX Migration Issues
There are no ULTRIX migration issues.
G.8.7 Thread Independent Services Interface
DIGITAL UNIX Version 4.0B introduces the Thread Independent Services
(TIS) application programming interface in the C run-time library libc.
TIS provides services that assist in the development of thread-safe libraries.
Thread synchronization may involve significant run-time cost, which is
undesirable in the absence of threads. TIS enables thread-safe libraries to
be built that are both efficient in the nonthreaded environment, yet provide
the necessary synchronization in the threaded environment.
When DECthreads (pthreads) are not active within the process, TIS
executes only the minimum steps necessary. Code running in a
nonthreaded environment does not encounter overhead incurred by the
run-time synchronization that is necessary when the same code is run in a
threaded environment. When DECthreads are active, the TIS functions
provide the necessary thread-safe synchronization.
G.8.7.1 ULTRIX Migration Issues
There are no ULTRIX migration issues.
G.8.8 High-Resolution Clock
DIGITAL UNIX Version 4.0B has an optional high-resolution clock. To
enable this option, add the following line to the kernel configuration file
and rebuild the kernel:
options MICRO_TIME
The system clock ( CLOCK_REALTIME) resolution as returned by
clock_getres will not change. Timer resolution remains the same.
However, time as returned by the clock_gettime routine will now be
extrapolated between the clock ticks. The granularity of the time returned
will now be in microseconds. The time values returned are SMP safe,
monotonically increasing, and have 1 microsecond as the apparent
resolution.
G.8.8.1 ULTRIX Migration Issues
There are no ULTRIX migration issues.
G–14 Migration from ULTRIX Version 4.5 to DIGITAL UNIX Version 4.0B