计时的性能分析

/******************************************************************************Module:  UserSyncCompare.cppNotices: Copyright (c) 2008 Jeffrey Richter & Christophe Nasarre******************************************************************************/#include "..\CommonFiles\CmnHdr.h"     /* See Appendix A. */#include <windows.h>#include <stdio.h>#include <tchar.h>// Stop watch class from Chapter 7class CStopwatch {public:   CStopwatch() {    QueryPerformanceFrequency(&m_liPerfFreq);    Start();   }   void Start() {    QueryPerformanceCounter(&m_liPerfStart);   }   // Returns # of milliseconds since Start was called   __int64 Now() const {         LARGE_INTEGER liPerfNow;      QueryPerformanceCounter(&liPerfNow);      return(((liPerfNow.QuadPart - m_liPerfStart.QuadPart) * 1000)          / m_liPerfFreq.QuadPart);      }private:   LARGE_INTEGER m_liPerfFreq;   // Counts per second   LARGE_INTEGER m_liPerfStart;  // Starting count};DWORD g_nIterations = 1000000;typedef void (CALLBACK* OPERATIONFUNC)();DWORD WINAPI ThreadIterationFunction(PVOID operationFunc) {OPERATIONFUNC op = (OPERATIONFUNC) operationFunc;   for (DWORD iteration = 0; iteration < g_nIterations; iteration++) {      op();   }     return 0;}void MeasureConcurrentOperation(   TCHAR* operationName, DWORD nThreads, OPERATIONFUNC operationFunc) {   HANDLE* phThreads = new HANDLE[nThreads];   SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_HIGHEST);   for (DWORD currentThread = 0; currentThread < nThreads; currentThread++) {      phThreads[currentThread] =          CreateThread(NULL, 0, ThreadIterationFunction, operationFunc, 0, NULL);   }   SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_NORMAL);   CStopwatch watch;   WaitForMultipleObjects(nThreads, phThreads, TRUE, INFINITE);   __int64 elapsedTime = watch.Now();   _tprintf(   TEXT("Threads=%u, Milliseconds=%u, Test=%s\n"),       nThreads, (DWORD)elapsedTime, operationName);   // Don't forget to clean up the thread handles   for (DWORD currentThread = 0; currentThread < nThreads; currentThread++) {      CloseHandle(phThreads[currentThread]);   }   delete phThreads;}// -----------------------------------------------------------// List of tests to run:// -----------------------------------------------------------// Reading from a volatile int with NO synchronization at all// Writing to an int using InterlockedIncrement// Reading from a volatile int using critical sections// Read from a volatile int using SRWLock// Read from a volatile int using Mutex// -----------------------------------------------------------volatile LONG gv_value = 0;// 'lValue': local variable is initialized but not referenced#pragma warning(disable:4189)void WINAPI VolatileReadCallback(){   LONG lValue = gv_value; }#pragma warning(default:4189)void WINAPI VolatileWriteCallback(){   gv_value = 0; }void WINAPI InterlockedIncrementCallback(){InterlockedIncrement(&gv_value);}CRITICAL_SECTION  g_cs;void WINAPI CriticalSectionCallback(){EnterCriticalSection(&g_cs);gv_value = 0;LeaveCriticalSection(&g_cs);}HANDLE g_hMutex;void WINAPI MutexCallback(){WaitForSingleObject(g_hMutex, INFINITE);gv_value = 0;ReleaseMutex(g_hMutex);}// Slim Reader/Writer Lock global variableSRWLOCK g_srwLock;void WINAPI SRWLockReadCallback() {AcquireSRWLockShared(&g_srwLock);gv_value = 0;ReleaseSRWLockShared(&g_srwLock);}void WINAPI SRWLockWriteCallback() {AcquireSRWLockExclusive(&g_srwLock);gv_value = 0;ReleaseSRWLockExclusive(&g_srwLock);}int _tmain(int argc, _TCHAR* argv[]) {   for (int nThreads = 1; nThreads <= 4; nThreads *= 2) {      MeasureConcurrentOperation(TEXT("Volatile Read"), nThreads, VolatileReadCallback);MeasureConcurrentOperation(TEXT("Volatile Write"), nThreads, VolatileWriteCallback);MeasureConcurrentOperation(TEXT("Interlocked Increment"), nThreads, InterlockedIncrementCallback);// Prepare the critical sectionInitializeCriticalSection(&g_cs);MeasureConcurrentOperation(TEXT("Critical Section"), nThreads, CriticalSectionCallback);// Don't forget to cleanupDeleteCriticalSection(&g_cs);      // Prepare the Slim Reader/Writer lockInitializeSRWLock(&g_srwLock);MeasureConcurrentOperation(TEXT("SRWLock Read"), nThreads, SRWLockReadCallback);MeasureConcurrentOperation(TEXT("SRWLock Write"), nThreads, SRWLockWriteCallback);// NOTE: You can't cleanup a Slim Reader/Writer lock// Prepare the mutexg_hMutex = CreateMutex(NULL, false, NULL);MeasureConcurrentOperation(TEXT("Mutex"), nThreads, MutexCallback);CloseHandle(g_hMutex);_tprintf(TEXT("\n"));}   system("pause");return(0);}

Threads=1, Milliseconds=33, Test=Volatile Read
Threads=1, Milliseconds=30, Test=Volatile Write
Threads=1, Milliseconds=47, Test=Interlocked Increment
Threads=1, Milliseconds=71, Test=Critical Section
Threads=1, Milliseconds=80, Test=SRWLock Read
Threads=1, Milliseconds=63, Test=SRWLock Write
Threads=1, Milliseconds=953, Test=Mutex


Threads=2, Milliseconds=34, Test=Volatile Read
Threads=2, Milliseconds=42, Test=Volatile Write
Threads=2, Milliseconds=67, Test=Interlocked Increment
Threads=2, Milliseconds=211, Test=Critical Section
Threads=2, Milliseconds=0, Test=SRWLock Read
Threads=2, Milliseconds=88, Test=SRWLock Write
Threads=2, Milliseconds=3668, Test=Mutex


Threads=4, Milliseconds=36, Test=Volatile Read
Threads=4, Milliseconds=83, Test=Volatile Write
Threads=4, Milliseconds=70, Test=Interlocked Increment
Threads=4, Milliseconds=374, Test=Critical Section
Threads=4, Milliseconds=184, Test=SRWLock Read
Threads=4, Milliseconds=198, Test=SRWLock Write
Threads=4, Milliseconds=8474, Test=Mutex


请按任意键继续. . .