TLS 线程局部变量, 网上一堆文章说比用锁要好, 为什么我测试了后和 CRITICAL_SECTION 差不多呢

2018-10-25 11:18:20 235 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

C++11 4种互斥锁性能对比：std::mutex vs recursive_mutex 在10万次锁操作下的耗时差异本文深入评测了C++11标准库中的四种互斥锁（std::mutex、std::recursive_mutex、std::timed_mutex和std::recursive_timed_mutex）在10万次锁操作下的性能差异。通过单线程、双线程和四线程场景的基准测试，揭示了基础std::mutex的最佳性能表现，并提供了针对不同应用场景的选型建议和优化技巧，帮助开发者高效处理多线程编程中的资源共享问题。阅读详情

之前开发的程序一直在用 TLS, 各线程玩各自的东西
但这段时间要优化一个服务端程序, 就想着能不能再优化一下 TLS 的东西
然后就写了下面的代码, 但运行结果看来, TLS 和 CRITICAL_SECTION 差不多的时间
反而很多时候要比 CS 慢.........................
难道是我打开的方式不对???

#include "stdafx.h"

#include <process.h>



static DWORD m_dwTLSIndex = 0;



static CRITICAL_SECTION m_lock;



#define MAX_ALLOCATE    1000000u

static volatile DWORD m_dwAllocCount = 0;



struct BUFFER

{

    BUFFER *next;

    BYTE data[16];

};



struct BUFFER_LIST

{

    BUFFER_LIST *next;

    BUFFER *pBuffers;

};



static BUFFER_LIST *m_pBufferList = NULL;

static BUFFER *m_pBuffers = NULL;



uintptr_t __stdcall _thread1(void *)

{

    BUFFER *p;

    BUFFER_LIST *pList = (BUFFER_LIST *)malloc(sizeof(BUFFER_LIST));

    ZeroMemory(pList, sizeof(BUFFER_LIST));



    ::EnterCriticalSection(&m_lock);

    pList->next = m_pBufferList;

    m_pBufferList = pList;

    ::LeaveCriticalSection(&m_lock);



    ::TlsSetValue(m_dwTLSIndex, pList);



    for (;;)

    {

        p = (BUFFER *)malloc(sizeof(BUFFER));

        p->data[0] = 0;



        pList = (BUFFER_LIST *)::TlsGetValue(m_dwTLSIndex);

        p->next = pList->pBuffers;

        pList->pBuffers = p;



        if (InterlockedIncrement(&m_dwAllocCount) >= MAX_ALLOCATE)

            break;

    }



    return 0;

}



uintptr_t __stdcall _thread2(void *)

{

    BUFFER *p;



    for (;;)

    {

        p = (BUFFER *)malloc(sizeof(BUFFER));

        p->data[0] = 0;



        ::EnterCriticalSection(&m_lock);

        p->next = m_pBuffers;

        m_pBuffers = p;

        ::LeaveCriticalSection(&m_lock);



        if (InterlockedIncrement(&m_dwAllocCount) >= MAX_ALLOCATE)

            break;

    }



    return 0;

}



void TestTLSData()

{

    ::InitializeCriticalSection(&m_lock);



    ULONGLONG ullBegin, ullEnd;

    SYSTEM_INFO si;

    ::GetSystemInfo(&si);



    DWORD dwThread = 0;

    DWORD dwCount = si.dwNumberOfProcessors;

    HANDLE *phThreads = new HANDLE[dwCount + 1];

    ZeroMemory(phThreads, sizeof(HANDLE) * (dwCount + 1));



    m_dwTLSIndex = ::TlsAlloc();



    ::GetSystemTimeAsFileTime((LPFILETIME)&ullBegin);



    dwThread = 0;

    while (dwCount--)

        phThreads[dwThread++] = (HANDLE)_beginthreadex(NULL, 0, _thread1, NULL, 0, NULL);



    ::WaitForMultipleObjects(dwThread, phThreads, TRUE, INFINITE);



    ::GetSystemTimeAsFileTime((LPFILETIME)&ullEnd);

    printf("Used TLS: %u.%04u ms\n", (DWORD)(ullEnd - ullBegin) / 10000, (DWORD)(ullEnd - ullBegin) % 10000);

    while (dwThread--)

        ::CloseHandle(phThreads[dwThread]);



    ::TlsFree(m_dwTLSIndex);



    BUFFER *n, *p;

    //BUFFER_LIST *pNext;

    //BUFFER_LIST *pList = m_pBufferList;

    //while (pList != NULL)

    //{

    //    pNext = pList->next;



    //    p = pList->pBuffers;

    //    while (p)

    //    {

    //        n = p->next;

    //        free(p);

    //        p = n;

    //    }



    //    free(pList);

    //    pList = pNext;

    //}



    m_dwAllocCount = 0;

    dwCount = si.dwNumberOfProcessors;

    ZeroMemory(phThreads, sizeof(HANDLE) * (dwCount + 1));



    ::GetSystemTimeAsFileTime((LPFILETIME)&ullBegin);



    dwThread = 0;

    while (dwCount--)

        phThreads[dwThread++] = (HANDLE)_beginthreadex(NULL, 0, _thread2, NULL, 0, NULL);



    ::WaitForMultipleObjects(dwThread, phThreads, TRUE, INFINITE);



    ::GetSystemTimeAsFileTime((LPFILETIME)&ullEnd);

    printf("Not used TLS: %u.%04u ms\n", (DWORD)(ullEnd - ullBegin) / 10000, (DWORD)(ullEnd - ullBegin) % 10000);

    while (dwThread--)

        ::CloseHandle(phThreads[dwThread]);



    //p = m_pBuffers;

    //while (p)

    //{

    //    n = p->next;

    //    free(p);

    //    p = n;

    //}



    ::DeleteCriticalSection(&m_lock);



    system("pause");

}