clock(3)
NAME
clock − report CPU time used
SYNTAX
long clock()
DESCRIPTION
The clock subroutine returns the amount of CPU time (in microseconds) used since the first call to clock. The time reported is the sum of the user and system times of the calling process and its terminated child processes for which it has executed wait(2) or system(3s).
The resolution of the clock is 16.667 milliseconds.
RESTRICTIONS
The value returned by clock is defined in microseconds for compatibility with systems that have CPU clocks with much higher resolution. Because of this, the value returned will wrap around after accumulating only 2147 seconds of CPU time (about 36 minutes).