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stream_lib.c

#include <stdio.h>
#include <math.h>
#include <float.h>
#include <limits.h>
#include <sys/time.h>
#include <stdlib.h>
#include "stream_lib.h"

static inline double mysecond()
{
      struct timeval tv;
      gettimeofday(&tv, NULL);
      return tv.tv_sec + tv.tv_usec * 1.e-6;
}


/*
 * Program: Stream
 * Programmer: Joe R. Zagar
 * Revision: 4.0-BETA, October 24, 1995
 * Original code developed by John D. McCalpin
 *
 * This program measures memory transfer rates in MB/s for simple 
 * computational kernels coded in C.  These numbers reveal the quality
 * of code generation for simple uncacheable kernels as well as showing
 * the cost of floating-point operations relative to memory accesses.
 *
 * INSTRUCTIONS:
 *
 *    1) Stream requires a good bit of memory to run.  Adjust the
 *          value of 'N' (below) to give a 'timing calibration' of 
 *          at least 20 clock-ticks.  This will provide rate estimates
 *          that should be good to about 5% precision.
 * 
 * Hacked by AK to be a library
 */

long N = 8000000;
#define NTIMES    10
#define OFFSET    0

/*
 *    3) Compile the code with full optimization.  Many compilers
 *       generate unreasonably bad code before the optimizer tightens
 *       things up.  If the results are unreasonably good, on the
 *       other hand, the optimizer might be too smart for me!
 *
 *         Try compiling with:
 *               cc -O stream_d.c second_wall.c -o stream_d -lm
 *
 *         This is known to work on Cray, SGI, IBM, and Sun machines.
 *
 *
 *    4) Mail the results to mccalpin@cs.virginia.edu
 *       Be sure to include:
 *          a) computer hardware model number and software revision
 *          b) the compiler flags
 *          c) all of the output from the test case.
 * Thanks!
 *
 */

int checktick();

# define HLINE "-------------------------------------------------------------\n"

# ifndef MIN
# define MIN(x,y) ((x)<(y)?(x):(y))
# endif
# ifndef MAX
# define MAX(x,y) ((x)>(y)?(x):(y))
# endif

static double *a, *b, *c;

static double rmstime[4] = { 0 }, maxtime[4] = {
0}, mintime[4] = {
FLT_MAX, FLT_MAX, FLT_MAX, FLT_MAX};

static char *label[4] = { "Copy:      ", "Scale:     ",
      "Add:       ", "Triad:     "
};
char *stream_names[] = { "Copy","Scale","Add","Triad" };

static double bytes[4];

int stream_verbose = 1;

#define Vprintf(x...) do { if (stream_verbose) printf(x); } while(0)

void stream_check(void)
{
      int quantum;
      int BytesPerWord;
      register int j;
      double t;

      /* --- SETUP --- determine precision and check timing --- */

      Vprintf(HLINE);
      BytesPerWord = sizeof(double);
      Vprintf("This system uses %d bytes per DOUBLE PRECISION word.\n",
             BytesPerWord);

      Vprintf(HLINE);
      Vprintf("Array size = %lu, Offset = %d\n", N, OFFSET);
      Vprintf("Total memory required = %.1f MB.\n",
             (3 * N * BytesPerWord) / 1048576.0);
      Vprintf("Each test is run %d times, but only\n", NTIMES);
      Vprintf("the *best* time for each is used.\n");

      /* Get initial value for system clock. */

      for (j = 0; j < N; j++) {
            a[j] = 1.0;
            b[j] = 2.0;
            c[j] = 0.0;
      }

      Vprintf(HLINE);

      if ((quantum = checktick()) >= 1)
            Vprintf("Your clock granularity/precision appears to be "
                   "%d microseconds.\n", quantum);
      else
            Vprintf("Your clock granularity appears to be "
                   "less than one microsecond.\n");

      t = mysecond();
      for (j = 0; j < N; j++)
            a[j] = 2.0E0 * a[j];
      t = 1.0E6 * (mysecond() - t);

      Vprintf("Each test below will take on the order"
             " of %d microseconds.\n", (int) t);
      Vprintf("   (= %d clock ticks)\n", (int) (t / quantum));
      Vprintf("Increase the size of the arrays if this shows that\n");
      Vprintf("you are not getting at least 20 clock ticks per test.\n");

      Vprintf(HLINE);

      Vprintf("WARNING -- The above is only a rough guideline.\n");
      Vprintf("For best results, please be sure you know the\n");
      Vprintf("precision of your system timer.\n");
      Vprintf(HLINE);
}

void stream_test(double *res)
{
      register int j, k;
      double scalar, times[4][NTIMES];

      /*  --- MAIN LOOP --- repeat test cases NTIMES times --- */

      scalar = 3.0;
      for (k = 0; k < NTIMES; k++) {
            times[0][k] = mysecond();
            for (j = 0; j < N; j++)
                  c[j] = a[j];
            times[0][k] = mysecond() - times[0][k];

            times[1][k] = mysecond();
            for (j = 0; j < N; j++)
                  b[j] = scalar * c[j];
            times[1][k] = mysecond() - times[1][k];

            times[2][k] = mysecond();
            for (j = 0; j < N; j++)
                  c[j] = a[j] + b[j];
            times[2][k] = mysecond() - times[2][k];

            times[3][k] = mysecond();
            for (j = 0; j < N; j++)
                  a[j] = b[j] + scalar * c[j];
            times[3][k] = mysecond() - times[3][k];
      }

      /*  --- SUMMARY --- */

      for (k = 0; k < NTIMES; k++) {
            for (j = 0; j < 4; j++) {
                  rmstime[j] =
                      rmstime[j] + (times[j][k] * times[j][k]);
                  mintime[j] = MIN(mintime[j], times[j][k]);
                  maxtime[j] = MAX(maxtime[j], times[j][k]);
            }
      }

      Vprintf
          ("Function      Rate (MB/s)   RMS time     Min time     Max time\n");
      for (j = 0; j < 4; j++) {
            double speed = 1.0E-06 * bytes[j] / mintime[j];

            rmstime[j] = sqrt(rmstime[j] / (double) NTIMES);

            Vprintf("%s%11.4f  %11.4f  %11.4f  %11.4f\n", label[j],
                  speed,
                   rmstime[j], mintime[j], maxtime[j]);

            if (res)
                  res[j] = speed;

      }
}

# define    M     20

int checktick()
{
      int i, minDelta, Delta;
      double t1, t2, timesfound[M];

/*  Collect a sequence of M unique time values from the system. */

      for (i = 0; i < M; i++) {
            t1 = mysecond();
            while (((t2 = mysecond()) - t1) < 1.0E-6);
            timesfound[i] = t1 = t2;
      }

/*
 * Determine the minimum difference between these M values.
 * This result will be our estimate (in microseconds) for the
 * clock granularity.
 */

      minDelta = 1000000;
      for (i = 1; i < M; i++) {
            Delta =
                (int) (1.0E6 * (timesfound[i] - timesfound[i - 1]));
            minDelta = MIN(minDelta, MAX(Delta, 0));
      }

      return (minDelta);
}

void stream_setmem(unsigned long size)
{ 
      N = (size - OFFSET) / (3*sizeof(double));
} 

long stream_memsize(void)
{ 
      return 3*(sizeof(double) * (N+OFFSET)) ;
} 

long stream_init(void *mem) 
{ 
      int i;

      for (i = 0; i < 4; i++) { 
            rmstime[i] = 0;
            maxtime[i] = 0;
            mintime[i] = FLT_MAX;
      }

      bytes[0] = 2 * sizeof(double) * N;
      bytes[1] = 2 * sizeof(double) * N;
      bytes[2] = 3 * sizeof(double) * N;
      bytes[3] = 3 * sizeof(double) * N;

      a = mem;
      b = (double *)mem +   (N+OFFSET);
      c = (double *)mem + 2*(N+OFFSET);
      stream_check();
      return 0;
} 

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