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  1. #include <iostream>
  2. #include <stdlib.h>
  3. #include <time.h>
  4.  
  5. typedef unsigned int uint32;
  6.  
  7. const int buf_size = 1024 * 10 * 1024 / 4;
  8. typedef int buf_type;
  9. volatile int read_hack;
  10.  
  11. void test4write( buf_type *buf )
  12. {
  13.   for ( int i = 0; i < buf_size; i++ )
  14.   {
  15.     buf[ i ] = 0;
  16.   };
  17. };
  18.  
  19. void test4read( buf_type *buf )
  20. {
  21.   buf_type res = 0;
  22.   for ( int i = 0; i < buf_size; i++ )
  23.   {
  24.     res += buf[ i ];
  25.   };
  26.   read_hack = res;
  27.   //std::cout << "res: " << res << "\n";
  28. };
  29.  
  30. typedef void (*fptr)(buf_type *);
  31.  
  32. void test( fptr fp, const char *label, buf_type *param )
  33. {
  34.   clock_t t = clock();
  35.   fp( param );
  36.   t = clock() - t;
  37.   double x = ((double)t) / CLOCKS_PER_SEC;
  38.   std::cout << label << " time: " << x << " sec => " << 1/x << " Gb/sec\n";
  39. };
  40.  
  41. int main() 
  42. {
  43.   buf_type *buf = new buf_type[ buf_size ];
  44.   test( test4write, "init write", buf );
  45.   test( test4write, "write", buf );
  46.   test( test4read, "read", buf );
  47.   test( test4write, "write", buf );
  48.   test( test4read, "read", buf );
  49.   test( test4write, "write", buf );
  50.   test( test4read, "read", buf );
  51.   delete[] buf;
  52.   return 0;
  53. };
Success #stdin #stdout 0.03s 3460KB
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stdin
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Standard input is empty
stdout
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init write time: 0.015534 sec => 64.3749 Gb/sec
write time: 0.004232 sec => 236.295 Gb/sec
read time: 0.003367 sec => 297 Gb/sec
write time: 0.003978 sec => 251.383 Gb/sec
read time: 0.003371 sec => 296.648 Gb/sec
write time: 0.003967 sec => 252.08 Gb/sec
read time: 0.003384 sec => 295.508 Gb/sec
https://ideone.com/i5CqVF
language:
C++ (gcc 8.3)
created:
9 years ago
visibility:
public

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