stream.c

/*-----------------------------------------------------------------------*/
/* Program: STREAM                                                       */
/* Revision: $Id: stream.c,v 5.10 2013/01/17 16:01:06 mccalpin Exp mccalpin $ */
/* Original code developed by John D. McCalpin                           */
/* Programmers: John D. McCalpin                                         */
/*              Joe R. Zagar                                             */
/*                                                                       */
/* This program measures memory transfer rates in MB/s for simple        */
/* computational kernels coded in C.                                     */
/*-----------------------------------------------------------------------*/
/* Copyright 1991-2013: John D. McCalpin                                 */
/*-----------------------------------------------------------------------*/
/* License:                                                              */
/*  1. You are free to use this program and/or to redistribute           */
/*     this program.                                                     */
/*  2. You are free to modify this program for your own use,             */
/*     including commercial use, subject to the publication              */
/*     restrictions in item 3.                                           */
/*  3. You are free to publish results obtained from running this        */
/*     program, or from works that you derive from this program,         */
/*     with the following limitations:                                   */
/*     3a. In order to be referred to as "STREAM benchmark results",     */
/*         published results must be in conformance to the STREAM        */
/*         Run Rules, (briefly reviewed below) published at              */
/*         http://www.cs.virginia.edu/stream/ref.html                    */
/*         and incorporated herein by reference.                         */
/*         As the copyright holder, John McCalpin retains the            */
/*         right to determine conformity with the Run Rules.             */
/*     3b. Results based on modified source code or on runs not in       */
/*         accordance with the STREAM Run Rules must be clearly          */
/*         labelled whenever they are published.  Examples of            */
/*         proper labelling include:                                     */
/*           "tuned STREAM benchmark results"                            */
/*           "based on a variant of the STREAM benchmark code"           */
/*         Other comparable, clear, and reasonable labelling is          */
/*         acceptable.                                                   */
/*     3c. Submission of results to the STREAM benchmark web site        */
/*         is encouraged, but not required.                              */
/*  4. Use of this program or creation of derived works based on this    */
/*     program constitutes acceptance of these licensing restrictions.   */
/*  5. Absolutely no warranty is expressed or implied.                   */
/*-----------------------------------------------------------------------*/
#include <float.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <sys/time.h>
#include <unistd.h>

/*-----------------------------------------------------------------------
 * INSTRUCTIONS:
 *
 *	1) STREAM requires different amounts of memory to run on different
 *           systems, depending on both the system cache size(s) and the
 *           granularity of the system timer.
 *     You should adjust the value of 'STREAM_ARRAY_SIZE' (below)
 *           to meet *both* of the following criteria:
 *       (a) Each array must be at least 4 times the size of the
 *           available cache memory. I don't worry about the difference
 *           between 10^6 and 2^20, so in practice the minimum array size
 *           is about 3.8 times the cache size.
 *           Example 1: One Xeon E3 with 8 MB L3 cache
 *               STREAM_ARRAY_SIZE should be >= 4 million, giving
 *               an array size of 30.5 MB and a total memory requirement
 *               of 91.5 MB.
 *           Example 2: Two Xeon E5's with 20 MB L3 cache each (using OpenMP)
 *               STREAM_ARRAY_SIZE should be >= 20 million, giving
 *               an array size of 153 MB and a total memory requirement
 *               of 458 MB.
 *       (b) The size should be large enough so that the 'timing calibration'
 *           output by the program is at least 20 clock-ticks.
 *           Example: most versions of Windows have a 10 millisecond timer
 *               granularity.  20 "ticks" at 10 ms/tic is 200 milliseconds.
 *               If the chip is capable of 10 GB/s, it moves 2 GB in 200 msec.
 *               This means the each array must be at least 1 GB, or 128M
 *elements.
 *
 *      Version 5.10 increases the default array size from 2 million
 *          elements to 10 million elements in response to the increasing
 *          size of L3 caches.  The new default size is large enough for caches
 *          up to 20 MB.
 *      Version 5.10 changes the loop index variables from "register int"
 *          to "ssize_t", which allows array indices >2^32 (4 billion)
 *          on properly configured 64-bit systems.  Additional compiler options
 *          (such as "-mcmodel=medium") may be required for large memory runs.
 *
 *      Array size can be set at compile time without modifying the source
 *          code for the (many) compilers that support preprocessor definitions
 *          on the compile line.  E.g.,
 *                gcc -O -DSTREAM_ARRAY_SIZE=100000000 stream.c -o stream.100M
 *          will override the default size of 10M with a new size of 100M
 *elements per array.
 */
#ifndef STREAM_ARRAY_SIZE
#define STREAM_ARRAY_SIZE 10000000
#endif

/*  2) STREAM runs each kernel "NTIMES" times and reports the *best* result
 *         for any iteration after the first, therefore the minimum value
 *         for NTIMES is 2.
 *      There are no rules on maximum allowable values for NTIMES, but
 *         values larger than the default are unlikely to noticeably
 *         increase the reported performance.
 *      NTIMES can also be set on the compile line without changing the source
 *         code using, for example, "-DNTIMES=7".
 */
#ifdef NTIMES
#if NTIMES <= 1
#define NTIMES 10
#endif
#endif
#ifndef NTIMES
#define NTIMES 10
#endif

/*  Users are allowed to modify the "OFFSET" variable, which *may* change the
 *         relative alignment of the arrays (though compilers may change the
 *         effective offset by making the arrays non-contiguous on some
 * systems). Use of non-zero values for OFFSET can be especially helpful if the
 *         STREAM_ARRAY_SIZE is set to a value close to a large power of 2.
 *      OFFSET can also be set on the compile line without changing the source
 *         code using, for example, "-DOFFSET=56".
 */
#ifndef OFFSET
#define OFFSET 0
#endif

/*
 *	3) Compile the code with 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!
 *
 *     For a simple single-core version, try compiling with:
 *            cc -O stream.c -o stream
 *     This is known to work on many, many systems....
 *
 *     To use multiple cores, you need to tell the compiler to obey the OpenMP
 *       directives in the code.  This varies by compiler, but a common example
 *is gcc -O -fopenmp stream.c -o stream_omp The environment variable
 *OMP_NUM_THREADS allows runtime control of the number of threads/cores used
 *when the resulting "stream_omp" program is executed.
 *
 *     To run with single-precision variables and arithmetic, simply add
 *         -DSTREAM_TYPE=float
 *     to the compile line.
 *     Note that this changes the minimum array sizes required --- see (1)
 *above.
 *
 *     The preprocessor directive "TUNED" does not do much -- it simply causes
 *the code to call separate functions to execute each kernel.  Trivial versions
 *       of these functions are provided, but they are *not* tuned -- they just
 *       provide predefined interfaces to be replaced with tuned code.
 *
 *
 *	4) Optional: Mail the results to mccalpin@cs.virginia.edu
 *	   Be sure to include info that will help me understand:
 *		a) the computer hardware configuration (e.g., processor model,
 *memory type) b) the compiler name/version and compilation flags c) any
 *run-time information (such as OMP_NUM_THREADS) d) all of the output from the
 *test case.
 *
 * Thanks!
 *
 *-----------------------------------------------------------------------*/

#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

#ifndef STREAM_TYPE
#define STREAM_TYPE double
#endif

static STREAM_TYPE a[STREAM_ARRAY_SIZE + OFFSET], b[STREAM_ARRAY_SIZE + OFFSET],
    c[STREAM_ARRAY_SIZE + OFFSET];

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

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

static double bytes[4] = {2 * sizeof(STREAM_TYPE) * STREAM_ARRAY_SIZE,
                          2 * sizeof(STREAM_TYPE) * STREAM_ARRAY_SIZE,
                          3 * sizeof(STREAM_TYPE) * STREAM_ARRAY_SIZE,
                          3 * sizeof(STREAM_TYPE) * STREAM_ARRAY_SIZE};

extern double mysecond();
extern void checkSTREAMresults();
#ifdef TUNED
extern void tuned_STREAM_Copy();
extern void tuned_STREAM_Scale(STREAM_TYPE scalar);
extern void tuned_STREAM_Add();
extern void tuned_STREAM_Triad(STREAM_TYPE scalar);
#endif
#ifdef _OPENMP
extern int omp_get_num_threads();
#endif

void write_result(const char* fname, const double* times, const double bytes) {
  FILE* results = fopen(fname, "w");
  if (!results) {
    printf("Error: Unable to create %s\n", fname);
    return;
  }
  fprintf(results, "IterTime,Bandwidth\n");

  for (int i = 0; i < NTIMES; i++) {
    fprintf(results, "%f,%f\n", times[i], 1.0E-06 * bytes / times[i]);
  }

  if (fclose(results)) printf("Error: Unable to write %s\n", fname);
}

int main() {
  int quantum, checktick();
  int BytesPerWord;
  int k;
  ssize_t j;
  STREAM_TYPE scalar;
  double t, times[4][NTIMES];

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

  printf(HLINE);
  printf("STREAM version $Revision: 5.10 $\n");
  printf(HLINE);
  BytesPerWord = sizeof(STREAM_TYPE);
  printf("This system uses %d bytes per array element.\n", BytesPerWord);

  printf(HLINE);
#ifdef N
  printf("*****  WARNING: ******\n");
  printf("      It appears that you set the preprocessor variable N when "
         "compiling this code.\n");
  printf("      This version of the code uses the preprocessor variable "
         "STREAM_ARRAY_SIZE to control the array size\n");
  printf("      Reverting to default value of STREAM_ARRAY_SIZE=%llu\n",
         (unsigned long long)STREAM_ARRAY_SIZE);
  printf("*****  WARNING: ******\n");
#endif

  printf("Array size = %llu (elements), Offset = %d (elements)\n",
         (unsigned long long)STREAM_ARRAY_SIZE, OFFSET);
  printf("Memory per array = %.1f MiB (= %.1f GiB).\n",
         BytesPerWord * ((double)STREAM_ARRAY_SIZE / 1024.0 / 1024.0),
         BytesPerWord * ((double)STREAM_ARRAY_SIZE / 1024.0 / 1024.0 / 1024.0));
  printf("Total memory required = %.1f MiB (= %.1f GiB).\n",
         (3.0 * BytesPerWord) * ((double)STREAM_ARRAY_SIZE / 1024.0 / 1024.),
         (3.0 * BytesPerWord) *
             ((double)STREAM_ARRAY_SIZE / 1024.0 / 1024. / 1024.));
  printf("Each kernel will be executed %d times.\n", NTIMES);
  printf(" The *best* time for each kernel (excluding the first iteration)\n");
  printf(" will be used to compute the reported bandwidth.\n");

#ifdef _OPENMP
  printf(HLINE);
#pragma omp parallel
  {
#pragma omp master
    {
      k = omp_get_num_threads();
      printf("Number of Threads requested = %i\n", k);
    }
  }
#endif

#ifdef _OPENMP
  k = 0;
#pragma omp parallel
#pragma omp atomic
  k++;
  printf("Number of Threads counted = %i\n", k);
#endif

  /* Get initial value for system clock. */
#pragma omp parallel for
  for (j = 0; j < STREAM_ARRAY_SIZE; j++) {
    a[j] = 1.0;
    b[j] = 2.0;
    c[j] = 0.0;
  }

  printf(HLINE);

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

  t = mysecond();
#pragma omp parallel for
  for (j = 0; j < STREAM_ARRAY_SIZE; j++)
    a[j] = 2.0E0 * a[j];
  t = 1.0E6 * (mysecond() - t);

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

  printf(HLINE);

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

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

  scalar = 3.0;
  for (k = 0; k < NTIMES; k++) {
#ifdef COPY
    times[0][k] = mysecond();
#ifdef TUNED
    tuned_STREAM_Copy();
#else
#pragma omp parallel for
    for (j = 0; j < STREAM_ARRAY_SIZE; j++)
      c[j] = a[j];
#endif
    times[0][k] = mysecond() - times[0][k];

#endif
#ifdef SCALE
    times[1][k] = mysecond();
#ifdef TUNED
    tuned_STREAM_Scale(scalar);
#else
#pragma omp parallel for
    for (j = 0; j < STREAM_ARRAY_SIZE; j++)
      b[j] = scalar * c[j];
#endif
    times[1][k] = mysecond() - times[1][k];

#endif
#ifdef ADD
    times[2][k] = mysecond();
#ifdef TUNED
    tuned_STREAM_Add();
#else
#pragma omp parallel for
    for (j = 0; j < STREAM_ARRAY_SIZE; j++)
      c[j] = a[j] + b[j];
#endif
    times[2][k] = mysecond() - times[2][k];

#endif
#ifdef TRIAD
    times[3][k] = mysecond();
#ifdef TUNED
    tuned_STREAM_Triad(scalar);
#else
#pragma omp parallel for
    for (j = 0; j < STREAM_ARRAY_SIZE; j++)
      a[j] = b[j] + scalar * c[j];
#endif
    times[3][k] = mysecond() - times[3][k];
#endif
  }

  /*	--- SUMMARY --- */

#ifdef COPY
  write_result("Copy.csv", times[0], bytes[0]);
#endif
#ifdef SCALE
  write_result("Scale.csv", times[1], bytes[1]);
#endif
#ifdef ADD
  write_result("Add.csv", times[2], bytes[2]);
#endif
#ifdef TRIAD
  write_result("Triad.csv", times[3], bytes[3]);
#endif

  for (k = 1; k < NTIMES; k++) /* note -- skip first iteration */
  {
    for (j = 0; j < 4; j++) {
      avgtime[j] = avgtime[j] + times[j][k];
      mintime[j] = MIN(mintime[j], times[j][k]);
      maxtime[j] = MAX(maxtime[j], times[j][k]);
    }
  }
  

  printf("Function    Best Rate MB/s  Avg time     Min time     Max time\n");
  for (j = 0; j < 4; j++) {
    avgtime[j] = avgtime[j] / (double)(NTIMES - 1);

    printf("%s%12.1f  %11.6f  %11.6f  %11.6f\n", label[j],
           1.0E-06 * bytes[j] / mintime[j], avgtime[j], mintime[j], maxtime[j]);
  }
  printf(HLINE);

  /* --- Check Results --- */
  checkSTREAMresults();
  printf(HLINE);

  return 0;
}

#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);
}

/* A gettimeofday routine to give access to the wall
   clock timer on most UNIX-like systems.  */

#include <sys/time.h>

double mysecond() {
  struct timeval tp;
  struct timezone tzp;
  int i;

  i = gettimeofday(&tp, &tzp);
  return ((double)tp.tv_sec + (double)tp.tv_usec * 1.e-6);
}

#ifndef abs
#define abs(a) ((a) >= 0 ? (a) : -(a))
#endif
void checkSTREAMresults() {
  STREAM_TYPE aj, bj, cj, scalar;
  STREAM_TYPE aSumErr, bSumErr, cSumErr;
  STREAM_TYPE aAvgErr, bAvgErr, cAvgErr;
  double epsilon;
  ssize_t j;
  int k, ierr, err;

  /* reproduce initialization */
  aj = 1.0;
  bj = 2.0;
  cj = 0.0;
  /* a[] is modified during timing check */
  aj = 2.0E0 * aj;
  /* now execute timing loop */
  scalar = 3.0;
  for (k = 0; k < NTIMES; k++) {
    cj = aj;
    bj = scalar * cj;
    cj = aj + bj;
    aj = bj + scalar * cj;
  }

  /* accumulate deltas between observed and expected results */
  aSumErr = 0.0;
  bSumErr = 0.0;
  cSumErr = 0.0;
  for (j = 0; j < STREAM_ARRAY_SIZE; j++) {
    aSumErr += abs(a[j] - aj);
    bSumErr += abs(b[j] - bj);
    cSumErr += abs(c[j] - cj);
    // if (j == 417) printf("Index 417: c[j]: %f, cj: %f\n",c[j],cj);	//
    // MCCALPIN
  }
  aAvgErr = aSumErr / (STREAM_TYPE)STREAM_ARRAY_SIZE;
  bAvgErr = bSumErr / (STREAM_TYPE)STREAM_ARRAY_SIZE;
  cAvgErr = cSumErr / (STREAM_TYPE)STREAM_ARRAY_SIZE;

  if (sizeof(STREAM_TYPE) == 4) {
    epsilon = 1.e-6;
  } else if (sizeof(STREAM_TYPE) == 8) {
    epsilon = 1.e-13;
  } else {
    printf("WEIRD: sizeof(STREAM_TYPE) = %lu\n", sizeof(STREAM_TYPE));
    epsilon = 1.e-6;
  }

  err = 0;
  if (abs(aAvgErr / aj) > epsilon) {
    err++;
    printf("Failed Validation on array a[], AvgRelAbsErr > epsilon (%e)\n",
           epsilon);
    printf("     Expected Value: %e, AvgAbsErr: %e, AvgRelAbsErr: %e\n", aj,
           aAvgErr, abs(aAvgErr) / aj);
    ierr = 0;
    for (j = 0; j < STREAM_ARRAY_SIZE; j++) {
      if (abs(a[j] / aj - 1.0) > epsilon) {
        ierr++;
#ifdef VERBOSE
        if (ierr < 10) {
          printf("         array a: index: %ld, expected: %e, observed: %e, "
                 "relative error: %e\n",
                 j, aj, a[j], abs((aj - a[j]) / aAvgErr));
        }
#endif
      }
    }
    printf("     For array a[], %d errors were found.\n", ierr);
  }
  if (abs(bAvgErr / bj) > epsilon) {
    err++;
    printf("Failed Validation on array b[], AvgRelAbsErr > epsilon (%e)\n",
           epsilon);
    printf("     Expected Value: %e, AvgAbsErr: %e, AvgRelAbsErr: %e\n", bj,
           bAvgErr, abs(bAvgErr) / bj);
    printf("     AvgRelAbsErr > Epsilon (%e)\n", epsilon);
    ierr = 0;
    for (j = 0; j < STREAM_ARRAY_SIZE; j++) {
      if (abs(b[j] / bj - 1.0) > epsilon) {
        ierr++;
#ifdef VERBOSE
        if (ierr < 10) {
          printf("         array b: index: %ld, expected: %e, observed: %e, "
                 "relative error: %e\n",
                 j, bj, b[j], abs((bj - b[j]) / bAvgErr));
        }
#endif
      }
    }
    printf("     For array b[], %d errors were found.\n", ierr);
  }
  if (abs(cAvgErr / cj) > epsilon) {
    err++;
    printf("Failed Validation on array c[], AvgRelAbsErr > epsilon (%e)\n",
           epsilon);
    printf("     Expected Value: %e, AvgAbsErr: %e, AvgRelAbsErr: %e\n", cj,
           cAvgErr, abs(cAvgErr) / cj);
    printf("     AvgRelAbsErr > Epsilon (%e)\n", epsilon);
    ierr = 0;
    for (j = 0; j < STREAM_ARRAY_SIZE; j++) {
      if (abs(c[j] / cj - 1.0) > epsilon) {
        ierr++;
#ifdef VERBOSE
        if (ierr < 10) {
          printf("         array c: index: %ld, expected: %e, observed: %e, "
                 "relative error: %e\n",
                 j, cj, c[j], abs((cj - c[j]) / cAvgErr));
        }
#endif
      }
    }
    printf("     For array c[], %d errors were found.\n", ierr);
  }
  if (err == 0) {
    printf("Solution Validates: avg error less than %e on all three arrays\n",
           epsilon);
  }
#ifdef VERBOSE
  printf("Results Validation Verbose Results: \n");
  printf("    Expected a(1), b(1), c(1): %f %f %f \n", aj, bj, cj);
  printf("    Observed a(1), b(1), c(1): %f %f %f \n", a[1], b[1], c[1]);
  printf("    Rel Errors on a, b, c:     %e %e %e \n", abs(aAvgErr / aj),
         abs(bAvgErr / bj), abs(cAvgErr / cj));
#endif
}

#ifdef TUNED
/* stubs for "tuned" versions of the kernels */
void tuned_STREAM_Copy() {
  ssize_t j;
#pragma omp parallel for
  for (j = 0; j < STREAM_ARRAY_SIZE; j++)
    c[j] = a[j];
}

void tuned_STREAM_Scale(STREAM_TYPE scalar) {
  ssize_t j;
#pragma omp parallel for
  for (j = 0; j < STREAM_ARRAY_SIZE; j++)
    b[j] = scalar * c[j];
}

void tuned_STREAM_Add() {
  ssize_t j;
#pragma omp parallel for
  for (j = 0; j < STREAM_ARRAY_SIZE; j++)
    c[j] = a[j] + b[j];
}

void tuned_STREAM_Triad(STREAM_TYPE scalar) {
  ssize_t j;
#pragma omp parallel for
  for (j = 0; j < STREAM_ARRAY_SIZE; j++)
    a[j] = b[j] + scalar * c[j];
}
/* end of stubs for the "tuned" versions of the kernels */
#endif