[C++杂谈]增加cpu loading

增加cpu loading

背景：在版本发布后需要在指定负载情况下测试程序性能

代码很简单，就是启动N个线程，每个线程做S次循环自增，然后再休眠U秒，如此往复。可以达到以模拟以下场景：

• 1. 在空负载的情况下将单核或者多核的cpu loading增加到指定阈值
• 2. 增加较多的线程数达到cpu上下文频繁切换的目的

代码

#include <chrono>
#include <iostream>
#include <array>
#include <thread>
#include <vector>


void loading_func(int32_t sleep_us,int32_t step)
{        
    for(int32_t index = 0;index <= step;++index)
    {

    }
    std::this_thread::sleep_for(std::chrono::milliseconds(sleep_us));
}


int main(int argc,char **argv)
{
    auto thread_func = [](int32_t sleep_us,int32_t step){
        while (true)
        {
            loading_func(sleep_us,step);
        }
        
    };

    if (argc != 4)
    {
        printf("usage:%s thread_count sleep_us inc_step\r\n",argv[0]);
        exit(1);
    }


    int32_t thread_count = std::atoi(argv[1]);
    int32_t sleep_us = std::atoi(argv[2]);
    int32_t inc_step = std::atoi(argv[3]);

    std::vector<std::thread> threads;

    for (int32_t i = 0; i < thread_count;++i)
    {
        threads.emplace_back(std::thread(thread_func,sleep_us,inc_step));
    }

    for (auto &t : threads)
    {
        t.join();
    }

    return 0;
}

cmakelists

project(cpuloading)

set(bin_name ${PROJECT_NAME})

#set(CMAKE_CXX_FLAGS "-pthread -rt")

aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR} SRC_FILES)

add_executable(${bin_name} ${SRC_FILES})

target_link_libraries(${bin_name} rt pthread)