ceph/src/boost/libs/fiber/performance/thread/overhead_create.cpp

   1
   2 //          Copyright Oliver Kowalke 2009.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 //    (See accompanying file LICENSE_1_0.txt or copy at
   5 //          http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #include <cstdlib>
   8 #include <iostream>
   9 #include <stdexcept>
  10 #include <thread>
  11
  12 #include <boost/cstdint.hpp>
  13 #include <boost/preprocessor.hpp>
  14
  15 #include "../clock.hpp"
  16
  17 #ifndef JOBS
  18 #define JOBS BOOST_PP_LIMIT_REPEAT
  19 #endif
  20
  21 #define JOIN(z, n, _) \
  22 { \
  23     time_point_type start( clock_type::now() ); \
  24     std::thread t( worker); \
  25     duration_type total = clock_type::now() - start; \
  26     total -= overhead; \
  27     result += total; \
  28     t.join(); \
  29 }
  30
  31 void worker() {}
  32
  33 duration_type measure( duration_type overhead)
  34 {
  35     std::thread( worker).join();
  36
  37     duration_type result = duration_type::zero();
  38
  39     BOOST_PP_REPEAT_FROM_TO(1, JOBS, JOIN, _)
  40
  41     result /= JOBS;  // loops
  42
  43     return result;
  44 }
  45
  46 int main( int argc, char * argv[])
  47 {
  48     try
  49     {
  50         duration_type overhead = overhead_clock();
  51         boost::uint64_t res = measure( overhead).count();
  52         std::cout << "average of " << res << " nano seconds" << std::endl;
  53
  54         return EXIT_SUCCESS;
  55     }
  56     catch ( std::exception const& e)
  57     { std::cerr << "exception: " << e.what() << std::endl; }
  58     catch (...)
  59     { std::cerr << "unhandled exception" << std::endl; }
  60     return EXIT_FAILURE;
  61 }