netwerk/test/TestWriteSpeed.cpp

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  37
  38 #include "prio.h"
  39 #include "prinrval.h"
  40 #include "prmem.h"
  41 #include <stdio.h>
  42 #include <math.h>
  43
  44 void
  45 NS_MeanAndStdDev(double n, double sumOfValues, double sumOfSquaredValues,
  46                  double *meanResult, double *stdDevResult)
  47 {
  48   double mean = 0.0, var = 0.0, stdDev = 0.0;
  49   if (n > 0.0 && sumOfValues >= 0) {
  50     mean = sumOfValues / n;
  51     double temp = (n * sumOfSquaredValues) - (sumOfValues * sumOfValues);
  52     if (temp < 0.0 || n <= 1)
  53       var = 0.0;
  54     else
  55       var = temp / (n * (n - 1));
  56     // for some reason, Windows says sqrt(0.0) is "-1.#J" (?!) so do this:
  57     stdDev = var != 0.0 ? sqrt(var) : 0.0;
  58   }
  59   *meanResult = mean;
  60   *stdDevResult = stdDev;
  61 }
  62
  63 int
  64 Test(const char* filename, PRInt32 minSize, PRInt32 maxSize,
  65      PRInt32 sizeIncrement, PRInt32 iterations)
  66 {
  67     fprintf(stdout, "      size  write:    mean     stddev      iters  total:    mean     stddev      iters\n");
  68     for (PRInt32 size = minSize; size <= maxSize; size += sizeIncrement) {
  69         // create a buffer of stuff to write
  70         char* buf = (char*)PR_Malloc(size);
  71         if (buf == NULL)
  72             return -1;
  73
  74         // initialize it with a pattern
  75         PRInt32 i;
  76         char hex[] = "0123456789ABCDEF";
  77         for (i = 0; i < size; i++) {
  78             buf[i] = hex[i & 0xF];
  79         }
  80
  81         double writeCount = 0, writeRate = 0, writeRateSquared = 0;
  82         double totalCount = 0, totalRate = 0, totalRateSquared = 0;
  83         for (i = 0; i < iterations; i++) {
  84             PRIntervalTime start = PR_IntervalNow();
  85
  86             char name[1024];
  87             sprintf(name, "%s_%d", filename, i);
  88             PRFileDesc* fd = PR_Open(name, PR_WRONLY | PR_CREATE_FILE | PR_TRUNCATE, 0664);
  89             if (fd == NULL)
  90                 return -1;
  91
  92             PRIntervalTime writeStart = PR_IntervalNow();
  93             PRInt32 rv = PR_Write(fd, buf, size);
  94             if (rv < 0) return rv;
  95             if (rv != size) return -1;
  96             PRIntervalTime writeStop = PR_IntervalNow();
  97
  98             PRStatus st = PR_Close(fd);
  99             if (st == PR_FAILURE) return -1;
 100
 101             PRIntervalTime stop = PR_IntervalNow();
 102
 103             PRIntervalTime writeTime = PR_IntervalToMilliseconds(writeStop - writeStart);
 104             if (writeTime > 0) {
 105                 double wr = size / writeTime;
 106                 writeRate += wr;
 107                 writeRateSquared += wr * wr;
 108                 writeCount++;
 109             }
 110
 111             PRIntervalTime totalTime = PR_IntervalToMilliseconds(stop - start);
 112             if (totalTime > 0) {
 113                 double t = size / totalTime;
 114                 totalRate += t;
 115                 totalRateSquared += t * t;
 116                 totalCount++;
 117             }
 118         }
 119
 120         PR_Free(buf);
 121
 122         double writeMean, writeStddev;
 123         double totalMean, totalStddev;
 124         NS_MeanAndStdDev(writeCount, writeRate, writeRateSquared,
 125                          &writeMean, &writeStddev);
 126         NS_MeanAndStdDev(totalCount, totalRate, totalRateSquared,
 127                          &totalMean, &totalStddev);
 128         fprintf(stdout, "%10d      %10.2f %10.2f %10d      %10.2f %10.2f %10d\n",
 129                 size, writeMean, writeStddev, (PRInt32)writeCount,
 130                 totalMean, totalStddev, (PRInt32)totalCount);
 131     }
 132     return 0;
 133 }
 134
 135 int
 136 main(int argc, char* argv[])
 137 {
 138     if (argc != 5) {
 139         printf("usage: %s <min buf size (K)> <max buf size (K)> <size increment (K)> <iterations>\n", argv[0]);
 140         return -1;
 141     }
 142     Test("y:\\foo",
 143          atoi(argv[1]) * 1024,
 144          atoi(argv[2]) * 1024,
 145          atoi(argv[3]) * 1024,
 146          atoi(argv[4]));
 147     return 0;
 148 }