PerfMonTestCpuCruncherAlg.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
// PerfMonTestCpuCruncherAlg.cxx 
// Implementation file for class PerfMonTest::CpuCruncherAlg
// Author: S.Binet<binet@cern.ch>
 
 
// STL includes
#include <chrono>
#include <cmath>
 
// FrameWork includes
#include "Gaudi/Property.h"
 
// PerfMonTests includes
#include "PerfMonTestCpuCruncherAlg.h"
 
using namespace PerfMonTest;
 
 
StatusCode CpuCruncherAlg::initialize()
{
  ATH_MSG_INFO ( "Initializing " << name() << "..." ) ;
  
  // Random number service
  m_distribution = std::normal_distribution<double>(m_meanCpuTime,m_rmsCpuTime);
 
  ATH_MSG_INFO ( "CPU usage configuration: <" 
                 << m_meanCpuTime << "> +/- "
                 << m_rmsCpuTime << " ms" ) ;
  
 
  return StatusCode::SUCCESS;
}
 
 
StatusCode CpuCruncherAlg::execute(const EventContext& /*ctx*/)
{  
  ATH_MSG_DEBUG ( "Executing " << name() << "..." ) ;
 
  // Volatile to avoid optimization
  volatile double test_result = 0.0;
 
  // Sample randomly - use w/ care
  double ms_interval = m_distribution(m_random);
 
  ATH_MSG_DEBUG ( "Will burn CPU for " << ms_interval << " milliseconds ..." );
 
  // Define the interval, do some math until the interval is exhausted
  std::chrono::duration<float, std::milli> chrono_interval(ms_interval);
 
  auto start = std::chrono::system_clock::now();
 
  while (std::chrono::system_clock::now() - start < chrono_interval)
    test_result += burn(5000);
 
  ATH_MSG_DEBUG ( "Test result sum is " << test_result );
 
  return StatusCode::SUCCESS;
}
 
double CpuCruncherAlg::burn(unsigned long nIterations = 10000000lu) {
 
  // Volatile to avoid optimization
  volatile double sum = 0.0;
 
  double val;
 
  for(auto idx = 0lu; idx < nIterations; ++idx) {
    val = (double) (idx + 1) / nIterations * 0.7854;
    sum += std::tan(std::log(val));
  }
 
  return sum;
}