ceph/src/boost/libs/context/performance/ucontext/performance.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 <cstddef>
   8 #include <cstdlib>
   9 #include <iostream>
  10 #include <stdexcept>
  11
  12 #include <boost/cstdint.hpp>
  13 #include <boost/program_options.hpp>
  14
  15 #include <ucontext.h>
  16
  17 #include "../bind_processor.hpp"
  18 #include "../clock.hpp"
  19 #include "../cycle.hpp"
  20 #include "../../example/simple_stack_allocator.hpp"
  21
  22 typedef boost::context::simple_stack_allocator<
  23             8 * 1024 * 1024, 64 * 1024, 8 * 1024
  24         >                                       stack_allocator;
  25
  26 boost::uint64_t jobs = 1000;
  27 ucontext_t uc, ucm;
  28
  29 static void fn()
  30 { while ( true) ::swapcontext( & uc, & ucm); }
  31
  32 duration_type measure_time()
  33 {
  34     // cache warum-up
  35     ::swapcontext( & ucm, & uc);
  36
  37     time_point_type start( clock_type::now() );
  38     for ( std::size_t i = 0; i < jobs; ++i) {
  39         ::swapcontext( & ucm, & uc);
  40     }
  41     duration_type total = clock_type::now() - start;
  42     total -= overhead_clock(); // overhead of measurement
  43     total /= jobs;  // loops
  44     total /= 2;  // 2x jump_fcontext
  45
  46     return total;
  47 }
  48
  49 #ifdef BOOST_CONTEXT_CYCLE
  50 cycle_type measure_cycles()
  51 {
  52     // cache warum-up
  53     ::swapcontext( & ucm, & uc);
  54
  55     cycle_type start( cycles() );
  56     for ( std::size_t i = 0; i < jobs; ++i) {
  57         ::swapcontext( & ucm, & uc);
  58     }
  59     cycle_type total = cycles() - start;
  60     total -= overhead_cycle(); // overhead of measurement
  61     total /= jobs;  // loops
  62     total /= 2;  // 2x jump_fcontext
  63
  64     return total;
  65 }
  66 #endif
  67
  68 int main( int argc, char * argv[])
  69 {
  70     try
  71     {
  72         bind_to_processor( 0);
  73
  74         boost::program_options::options_description desc("allowed options");
  75         desc.add_options()
  76             ("help", "help message")
  77             ("jobs,j", boost::program_options::value< boost::uint64_t >( & jobs), "jobs to run");
  78
  79         boost::program_options::variables_map vm;
  80         boost::program_options::store(
  81                 boost::program_options::parse_command_line(
  82                     argc,
  83                     argv,
  84                     desc),
  85                 vm);
  86         boost::program_options::notify( vm);
  87
  88         if ( vm.count("help") ) {
  89             std::cout << desc << std::endl;
  90             return EXIT_SUCCESS;
  91         }
  92
  93         stack_allocator stack_alloc;
  94         ::getcontext( & uc);
  95         uc.uc_stack.ss_sp = stack_alloc.allocate( stack_allocator::default_stacksize() );
  96         uc.uc_stack.ss_size = stack_allocator::default_stacksize();
  97         ::makecontext( & uc, fn, 7);
  98
  99         boost::uint64_t res = measure_time().count();
 100         std::cout << "average of " << res << " nano seconds" << std::endl;
 101 #ifdef BOOST_CONTEXT_CYCLE
 102         res = measure_cycles();
 103         std::cout << "average of " << res << " cpu cycles" << std::endl;
 104 #endif
 105
 106         return EXIT_SUCCESS;
 107     }
 108     catch ( std::exception const& e)
 109     { std::cerr << "exception: " << e.what() << std::endl; }
 110     catch (...)
 111     { std::cerr << "unhandled exception" << std::endl; }
 112     return EXIT_FAILURE;
 113 }