Simple process to discover how CPU usage stats are aggregated with different tools

show_cpu_usage.cpp

// Simple test to discover how process stats aggregate CPU usage
// Building: g++ -std=c++11 main.cpp -o mymain -lpthread

#include <chrono>
#include <cmath>
#include <cstdlib>
#include <iostream>
#include <thread>

volatile float a, b;

void be_lazy() {
  while(true) {
    b = rand();
    std::this_thread::sleep_for(std::chrono::seconds(1));
  }
}

void do_work() {
  while(true) {
    a = sqrt(rand()/2.0);
  }
}

int main() {
  std::thread worker {do_work};
  std::thread busy_worker {do_work};
  std::thread lazy_worker {be_lazy};
  do_work();
  worker.join();
  busy_worker.join();
  lazy_worker.join();
  return 0;
}