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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #include <time.h>
  5.  
  6. #define COUNT1 262144   // 2^18
  7. #define COUNT2 262145   // 2^18 + 1
  8. #define COUNT3 262154   // 2^18 + 10
  9. #define REPEATS 10000
  10.  
  11. void benchmark_copy(const int *src, int *dst, size_t count, const char *label) {
  12.     size_t size_bytes = count * sizeof(int);
  13.  
  14.     clock_t start = clock();
  15.     for (int i = 0; i < REPEATS; ++i) {
  16.         memcpy(dst, src, size_bytes);
  17.     }
  18.     clock_t end = clock();
  19.  
  20.     double total_sec = (double)(end - start) / CLOCKS_PER_SEC;
  21.     printf("%s: Copied %zu bytes (%zu ints) %d times\n", label, size_bytes, count, REPEATS);
  22.     printf("%s: Total time: %.6f sec\n", label, total_sec);
  23.  
  24.     // Prevent optimizing away some stuff
  25.     printf("%d \n", dst[14]);
  26. }
  27.  
  28. int main(void) {
  29.     static int src[COUNT3], dst[COUNT3];
  30.  
  31.     for (size_t i = 0; i < COUNT3; ++i) src[i] = (int)i;
  32.  
  33.     // Do all benchmarks twice just in case
  34.     benchmark_copy(src, dst, COUNT1, "COUNT1 (2^18)");
  35.     benchmark_copy(src, dst, COUNT1, "COUNT1 (2^18)");
  36.     benchmark_copy(src, dst, COUNT2, "COUNT2 (2^18 + 1)");
  37.     benchmark_copy(src, dst, COUNT2, "COUNT2 (2^18 + 1)");
  38.     benchmark_copy(src, dst, COUNT3, "COUNT3 (2^18 + 10)");
  39.     benchmark_copy(src, dst, COUNT3, "COUNT3 (2^18 + 10)");
  40.  
  41.     return 0;
  42. }
Success #stdin #stdout 3.36s 5312KB
comments (?)
stdin 
Standard input is empty
stdout 
COUNT1 (2^18): Copied 1048576 bytes (262144 ints) 10000 times
COUNT1 (2^18): Total time: 0.569267 sec
14 
COUNT1 (2^18): Copied 1048576 bytes (262144 ints) 10000 times
COUNT1 (2^18): Total time: 0.558774 sec
14 
COUNT2 (2^18 + 1): Copied 1048580 bytes (262145 ints) 10000 times
COUNT2 (2^18 + 1): Total time: 0.560326 sec
14 
COUNT2 (2^18 + 1): Copied 1048580 bytes (262145 ints) 10000 times
COUNT2 (2^18 + 1): Total time: 0.554844 sec
14 
COUNT3 (2^18 + 10): Copied 1048616 bytes (262154 ints) 10000 times
COUNT3 (2^18 + 10): Total time: 0.544589 sec
14 
COUNT3 (2^18 + 10): Copied 1048616 bytes (262154 ints) 10000 times
COUNT3 (2^18 + 10): Total time: 0.565179 sec
14
https://ideone.com/2jp9Hc
language:
C (gcc 8.3)
created:
304 days ago
visibility:
secret

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