I am trying to compare the computation time for performance comparison using different C libraries with gettimeofday() by including time.h and sys/time.h header files.
I used gettimeofday() at the start and end of my computation and took the difference. But each time I execute my C code, I get fluctuating time as answer. For example
0.007 sec,
0.004 sec,
0.009 sec etc.
Is there a way I could take the average of 50 such results other than manually make 50 such executions and taking the average of all results.
But each time I execute my C code, I get fluctuating time as answer.
This fluctuation is unrelated to C or to gettimeofday. Current processors and operating systems make such execution time fluctuate (e.g. because cache misses or branch prediction may be non-deterministic, and because context switches, preemption, page faults, interrupts etc... happen at any time).
In practice, read carefully time(7) (maybe you also want to use clock_gettime(2) and/or clock(3) and/or time(1)...). Set-up your benchmark to last at least one second (so repeat your benchmarked functions many times). Run several benchmarks and several times the same benchmark.