PAPI_flops.c

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/*****************************************************************************
 * This example demonstrates the usage of the function PAPI_flops_rate       *
 * which measures the number of floating point operations executed and the   *
 * MegaFlop rate(defined as the number of floating point operations per      *
 * microsecond). To use PAPI_flops_rate you need to have floating point      *
 * operations events supported by the platform.                               *
 *****************************************************************************/
 
/*****************************************************************************
 * The first call to PAPI_flops_rate initializes the PAPI library, set up    *
 * the counters to monitor the floating point operations event, and start    *
 * the counters. Subsequent calls will read the counters and return          *
 * real time, process time, floating point operations, and the Mflops/s rate *
 * since the latest call to PAPI_flops_rate.                                 *
 *****************************************************************************/
 
 
#include <stdio.h>
#include <stdlib.h>
#include "papi.h"
 
int your_slow_code();
 
int main()
{ 
  float real_time, proc_time,mflops;
  long long flpops;
  float ireal_time, iproc_time, imflops;
  long long iflpops;
  int retval;
 
  /***********************************************************************
   * If PAPI_FP_OPS is a derived event in your platform, then your       * 
   * platform must have at least three counters to support               *
   * PAPI_flops_rate, because PAPI needs one counter for cycles. So in   *
   * UltraSparcIII, even though the platform supports PAPI_FP_OPS,       *
   * UltraSparcIII only has two available hardware counters, and         *
   * PAPI_FP_OPS is a derived event that requires both of them, so       *
   * PAPI_flops_rate returns an error.                                   *
   ***********************************************************************/
  if((retval=PAPI_flops_rate(PAPI_FP_OPS,&ireal_time,&iproc_time,&iflpops,&imflops)) < PAPI_OK)
  { 
    printf("Could not initialise PAPI_flops \n");
    printf("Your platform may not support floating point operation event.\n"); 
    printf("retval: %d\n", retval);
    exit(1);
  }
 
  your_slow_code();
 
  
  if((retval=PAPI_flops_rate(PAPI_FP_OPS,&real_time, &proc_time, &flpops, &mflops))<PAPI_OK)
  {    
    printf("retval: %d\n", retval);
    exit(1);
  }
 
 
  printf("Real_time: %f Proc_time: %f flpops: %lld MFLOPS: %f\n", 
         real_time, proc_time,flpops,mflops);
 
  exit(0);
}
 
int your_slow_code()
{
  int i;
  double  tmp=1.1;
 
  for(i=1; i<2000; i++)
  { 
    tmp=(tmp+100)/i;
  }
  return 0;
}