Re: [PATCH] stdlib: reorganize stdlib Makefile routines by functionality

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 01/04/24 08:47, abush wang wrote:
> This is test:
> ```
> uint64_t getnsecs() {
>     uint32_t lo, hi;
>     __asm__ __volatile__ (
>         "rdtsc" : "=a"(lo), "=d"(hi)
>     );  
>     return ((uint64_t)hi << 32) | lo;
> }
> 
> int main() {
>     const int num_iterations = 1;

This low number of iteration makes the benchmark pretty much useless
on modern hardware with frequency scaling.  By raising to something
like 1000000000 I see no variation on my workstation (Ryzen 5900).

>     uint64_t start, end, total_time = 0;
> 
>     start = getnsecs();
>     for (int i = 0; i < num_iterations; i++) {
>         (void) lrand48();
>     }
>     end = getnsecs();
>     total_time += (end - start);
> 
>     printf("Average time for lrand48: %lu cycles\n", total_time / num_iterations);
>     return 0;
> }
> ```
> before:
> Average time for lrand48: 21418 cycles
> 
> after:
> Average time for lrand48: 9892 cycles