ceph/src/boost/libs/context/performance/zeit.hpp

   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 #ifndef ZEIT_H
   8 #define ZEIT_H
   9
  10 #include <time.h>
  11
  12 #include <algorithm>
  13 #include <numeric>
  14 #include <cstddef>
  15 #include <vector>
  16
  17 #include <boost/assert.hpp>
  18 #include <boost/bind.hpp>
  19 #include <boost/cstdint.hpp>
  20
  21 typedef boost::uint64_t zeit_t;
  22
  23 inline
  24 zeit_t zeit()
  25 {
  26     timespec t;
  27     ::clock_gettime( CLOCK_PROCESS_CPUTIME_ID, & t);
  28     return t.tv_sec * 1000000000 + t.tv_nsec;
  29 }
  30
  31 struct measure_zeit
  32 {
  33     zeit_t operator()()
  34     {
  35         zeit_t start( zeit() );
  36         return zeit() - start;
  37     }
  38 };
  39
  40 inline
  41 zeit_t overhead_zeit()
  42 {
  43     std::size_t iterations( 10);
  44     std::vector< zeit_t >  overhead( iterations, 0);
  45     for ( std::size_t i( 0); i < iterations; ++i)
  46         std::generate(
  47             overhead.begin(), overhead.end(),
  48             measure_zeit() );
  49     BOOST_ASSERT( overhead.begin() != overhead.end() );
  50     return std::accumulate( overhead.begin(), overhead.end(), 0) / iterations;
  51 }
  52
  53 #endif // ZEIT_H