ceph/src/boost/libs/fiber/performance/thread/overhead_yield.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     std::thread( worker, overhead, & result).join();
  23
  24 void worker( duration_type overhead, duration_type * result)
  25 {
  26     time_point_type start( clock_type::now() );
  27     std::this_thread::yield();
  28     duration_type total = clock_type::now() - start;
  29     total -= overhead;
  30     * result += total;
  31 }
  32
  33 duration_type measure( duration_type overhead)
  34 {
  35     duration_type result = duration_type::zero();
  36
  37     std::thread( worker, overhead, & result).join();
  38
  39     result = duration_type::zero();
  40
  41     BOOST_PP_REPEAT_FROM_TO(1, JOBS, JOIN, _)
  42
  43     result /= JOBS;  // loops
  44
  45     return result;
  46 }
  47
  48 int main( int argc, char * argv[])
  49 {
  50     try
  51     {
  52         duration_type overhead = overhead_clock();
  53         boost::uint64_t res = measure( overhead).count();
  54         std::cout << "average of " << res << " nano seconds" << std::endl;
  55
  56         return EXIT_SUCCESS;
  57     }
  58     catch ( std::exception const& e)
  59     { std::cerr << "exception: " << e.what() << std::endl; }
  60     catch (...)
  61     { std::cerr << "unhandled exception" << std::endl; }
  62     return EXIT_FAILURE;
  63 }