Calculating the elapsed wall clock time of a program is helpful to determine how much time it actually takes for a program to complete.
Measure wall clock time in c.
For that you will have to use chronometers.
The openmp system provides a function used as follows.
Wtime a c function which returns a reading of the wall clock time.
For parallel programming the important thing to measure is the elapsed wallclock time.
The easy method is to take the time the program ends and then subtract the time the program starts.
There are a lot of ways to measure time in computer science but as a general rule of thumb you should always use a clock that measures the elapsed real time or wall time.
Include sys time h int gettimeofday struct timeval restrict tp void restrict tzp.
To obtain cpu times use the win32 getprocesstimes function.
For example if the cpu is shared by other processes std clock time may advance slower than wall clock.
The system s notion of the current greenwich time and the current time zone.
In all multivalue basic languages you can use the time function to return the number of seconds from midnight.
The clock function tells how much wall clock time has passed since the crt initialization during process start.
The clock gettime function gets the current time of the clock specified by clock id and puts it into the buffer pointed to by tp.
Note that this function does not strictly conform to iso c which specifies net cpu time as the return value.
Std clock time may advance faster or slower than the wall clock depending on the execution resources given to the program by the operating system.
Tp parameter points to a structure containing atleast the following members.
Using clock gettime function in c c.
Do the work.
Following is a sample c program where we measure time taken by fun.
Cpu time used double end start clocks per sec.
The obvious one is gettimeofday.
This can be found by subtracting an initial reading of the wallclock time from a final one.
End clock.
As it turns out c has many functions available to get the current time.
Int clock gettime clockid t clock id struct timespec tp.
Fortunately all mpi implementations provide you with such a clock.
Prototype syntax.