[ Thanks to IdaAshley for this link.
]
“Application programs commonly use at least one form of time
measurement (for example, transaction time stamps). For that
purpose, POSIX libraries provide timing functions, such as
gettimeofday, which give an easy-to-use interface to application
programmers. When the application makes an intensive use of timing
functions, a more efficient implementation of the timing routines
can improve the overall performance of the program. This can be
invaluable for lower-level tasks such as code profiling or precise
delays in device drivers and other time-critical code.“On the Power Architecture platform, it is possible to further
improve on the performance delivered by gettimeofday…”