ceph/src/boost/libs/random/performance/nondet_random_speed.cpp

   1 /* boost nondet_random_speed.cpp performance test
   2  *
   3  * Copyright Jens Maurer 2000
   4  * Distributed under the Boost Software License, Version 1.0. (See
   5  * accompanying file LICENSE_1_0.txt or copy at
   6  * http://www.boost.org/LICENSE_1_0.txt)
   7  *
   8  * $Id$
   9  *
  10  */
  11
  12 #include <iostream>
  13 #include <string>
  14 #include <boost/timer.hpp>
  15 #include <boost/random/random_device.hpp>
  16
  17 // set to your CPU frequency
  18 static const double cpu_frequency = 1.87 * 1e9;
  19
  20 static void show_elapsed(double end, int iter, const std::string & name)
  21 {
  22   double usec = end/iter*1e6;
  23   double cycles = usec * cpu_frequency/1e6;
  24   std::cout << name << ": "
  25             << usec*1e3 << " nsec/loop = "
  26             << cycles << " CPU cycles"
  27             << std::endl;
  28 }
  29
  30 template<class Result, class RNG>
  31 static void timing(RNG & rng, int iter, const std::string& name)
  32 {
  33   volatile Result tmp; // make sure we're not optimizing too much
  34   boost::timer t;
  35   for(int i = 0; i < iter; i++)
  36     tmp = rng();
  37   show_elapsed(t.elapsed(), iter, name);
  38 }
  39
  40 template<class RNG>
  41 void run(int iter, const std::string & name)
  42 {
  43   RNG rng;
  44   timing<long>(rng, iter, name);
  45 }
  46
  47 int main(int argc, char*argv[])
  48 {
  49   if(argc != 2) {
  50     std::cerr << "usage: " << argv[0] << " iterations" << std::endl;
  51     return 1;
  52   }
  53
  54   int iter = std::atoi(argv[1]);
  55
  56   boost::random::random_device dev;
  57   timing<unsigned int>(dev, iter, "random_device");
  58
  59   return 0;
  60 }