Strange profiler behavior: same functions, different performances
- by arthurprs
I was learning to use gprof and then i got weird results for this code:
int one(int a, int b)
{
return a / (b + 1);
}
int two(int a, int b)
{
return a / (b + 1);
}
int main()
{
for (int i = 1; i < 30000000; i++)
{
two(i, i * 2);
one(i, i * 2);
}
return 0;
}
and this is the profiler output
% cumulative self self total
time seconds seconds calls ns/call ns/call name
48.39 0.90 0.90 29999999 30.00 30.00 one(int, int)
40.86 1.66 0.76 29999999 25.33 25.33 two(int, int)
10.75 1.86 0.20 main
If i call one then two the result is the inverse, two takes more time than one
both are the same functions, but the first calls always take less time then the second
Why is that?
Note: The assembly code is exactly the same and code is being compiled with no optimizations
