Two methods for calculating program running time in Linux

Two methods for calculating the program running time in Linux: general Linux technology-Linux programming and kernel information. For details, refer to the following section. 1. Here is what I see online:


Sometimes we need to calculate the execution time of the program. For example, we need to analyze the algorithm time.

... You can use the following function at this time.

# Include
Int gettimeofday (struct timeval * TV, struct timezone * tz );
Strut timeval {
Long TV _sec;/* seconds */
Long TV _usec;/* Number of microseconds */
};
Gettimeofday stores the time in the Structure TV. tz Is generally replaced by NULL.
# Include # Include # Include Void function ()
{
Unsigned int I, j;
Double y;
For (I = 0; I <1000; I ++)
For (j = 0; j <1000; j ++)
Y = sin (double) I );
}
Main ()
{
Struct timeval tpstart, tpend;
Float timeuse;
Gettimeofday (& tpstart, NULL );
Function ();
Gettimeofday (& tpend, NULL );
Timeuse = 1000000 * (tpend. TV _sec-tpstart. TV _sec) +
TV _usec-tpstart. TV _usec;
Timeuse/= 1000000;
Printf ("Used Time: % f \ n", timeuse );
Exit (0 );
}


This program outputs the execution time of the function. We can use this to test the system performance or calculate the function.

The output result on my machine is: Used Time: 0.556070.


2. The second is what I often use:

Add time before executing the program, for example, input time./abc.

I don't know why the first method is widely introduced on the internet ......