计算Windows中特定进程的上下文切换 [英] Counting Context Switches for Specific Process in Windows

问题描述

我想做的是编写一个小程序，该程序连续不断地计算在足够小的时间单位内特定进程经历的上下文切换的次数。我已经在 Process Explorer软件中观察到了此功能，因此我知道这绝对是可能的。

What I would like to do is write a small program that continuously live counts the number of context switches that a specific process experiences per a sufficiently small unit of time. I have observed this functionality within the software "Process Explorer", so I know it is definitely possible.

不幸的是，我对如何开始编写此代码一无所知，到目前为止，仍然无法在线找到任何有用的代码片段。因此，一个实现每个进程和每个单位时间的实时上下文切换计数的小型工作示例对我将非常有用。

Unfortunately, I have very little idea of how to begin coding this and have so far been unable to find any helpful code snippets online. Thus, a small working example implementing a per process and per unit time live context switch count would be immensely helpful for me.

推荐答案

这是一种实现方法-每秒打印出记事本线程0使用的上下文切换量（您可以在CounterPathBuffer初始化中替换所需的任何进程和线程号）：

Here's one way to do it - This will print the amount of context switches used by thread 0 of notepad (you can substitute any process and thread number you want in the CounterPathBuffer initialization) every second:

#include "stdafx.h"
#include <iostream>
#include <windows.h>
#include <stdio.h>
#include <conio.h>
#include <pdh.h>
#include <pdhmsg.h>

#pragma comment(lib, "pdh.lib")
using namespace std;
CONST ULONG SAMPLE_INTERVAL_MS    = 1000;
CONST PWSTR BROWSE_DIALOG_CAPTION = L"Select a counter to monitor.";

void wmain(void)
{
    PDH_STATUS Status;
    HQUERY Query = NULL;
    HCOUNTER Counter;
    PDH_FMT_COUNTERVALUE DisplayValue;
    DWORD CounterType;
    SYSTEMTIME SampleTime;
    PDH_BROWSE_DLG_CONFIG BrowseDlgData;
    WCHAR CounterPathBuffer[PDH_MAX_COUNTER_PATH] = L"\\\\ComputerNameGoesHere\\Thread(notepad/0)\\Context Switches/sec";


    //
    // Create a query.
    //

    Status = PdhOpenQuery(NULL, NULL, &Query);
    if (Status != ERROR_SUCCESS) 
    {
       wprintf(L"\nPdhOpenQuery failed with status 0x%x.", Status);
       goto Cleanup;
    }

    //
    // Initialize the browser dialog window settings.
    //



    ZeroMemory(&BrowseDlgData, sizeof(PDH_BROWSE_DLG_CONFIG));

    BrowseDlgData.bIncludeInstanceIndex = FALSE;
    BrowseDlgData.bSingleCounterPerAdd = TRUE;
    BrowseDlgData.bSingleCounterPerDialog = TRUE;
    BrowseDlgData.bLocalCountersOnly = FALSE;
    BrowseDlgData.bWildCardInstances = TRUE;
    BrowseDlgData.bHideDetailBox = TRUE;
    BrowseDlgData.bInitializePath = FALSE;
    BrowseDlgData.bDisableMachineSelection = FALSE;
    BrowseDlgData.bIncludeCostlyObjects = FALSE;
    BrowseDlgData.bShowObjectBrowser = FALSE;
    BrowseDlgData.hWndOwner = NULL;
    BrowseDlgData.szReturnPathBuffer = CounterPathBuffer;
    BrowseDlgData.cchReturnPathLength = PDH_MAX_COUNTER_PATH;
    BrowseDlgData.pCallBack = NULL;
    BrowseDlgData.dwCallBackArg = 0;
    BrowseDlgData.CallBackStatus = ERROR_SUCCESS;
    BrowseDlgData.dwDefaultDetailLevel = PERF_DETAIL_WIZARD;
    BrowseDlgData.szDialogBoxCaption = BROWSE_DIALOG_CAPTION;

    //
    // Add the selected counter to the query.
    //


    Status = PdhAddCounter(Query, CounterPathBuffer, 0, &Counter);
    if (Status != ERROR_SUCCESS) 
    {
        wprintf(L"\nPdhAddCounter failed with status 0x%x.", Status);
        goto Cleanup;
    }

    //
    // Most counters require two sample values to display a formatted value.
    // PDH stores the current sample value and the previously collected
    // sample value. This call retrieves the first value that will be used
    // by PdhGetFormattedCounterValue in the first iteration of the loop
    // Note that this value is lost if the counter does not require two
    // values to compute a displayable value.
    //

    Status = PdhCollectQueryData(Query);
    if (Status != ERROR_SUCCESS) 
    {
        wprintf(L"\nPdhCollectQueryData failed with 0x%x.\n", Status);
        goto Cleanup;
    }

    //
    // Print counter values until a key is pressed.
    //

    while (!_kbhit()) 
    {
        Sleep(SAMPLE_INTERVAL_MS);

        GetLocalTime(&SampleTime);

        Status = PdhCollectQueryData(Query);
        if (Status != ERROR_SUCCESS) 
        {
            wprintf(L"\nPdhCollectQueryData failed with status 0x%x.", Status);
        }

        wprintf(L"\n\"%2.2d/%2.2d/%4.4d %2.2d:%2.2d:%2.2d.%3.3d\"",
                SampleTime.wMonth,
                SampleTime.wDay,
                SampleTime.wYear,
                SampleTime.wHour,
                SampleTime.wMinute,
                SampleTime.wSecond,
                SampleTime.wMilliseconds);

        //
        // Compute a displayable value for the counter.
        //

        Status = PdhGetFormattedCounterValue(Counter,
                                             PDH_FMT_DOUBLE,
                                             &CounterType,
                                             &DisplayValue);
        if (Status != ERROR_SUCCESS) 
        {
            wprintf(L"\nPdhGetFormattedCounterValue failed with status 0x%x.", Status);
            goto Cleanup;
        }


        wprintf(L",\"%.20g\"", DisplayValue.doubleValue);
    }

Cleanup:

    //
    // Close the query.
    //

    if (Query) 
    {
       PdhCloseQuery(Query);
    }

    int x;
    cin >>x;
}

大多数代码都来自以下来源： msdn.microsoft.com/en-us/library/aa371886%28v=vs。 85％29.aspx 。我想缩短对上下文开关进行连续检查之间的时间（使其少于一秒钟）。如果有人对如何操作有任何想法，那就太好了。

Most of the code is from this source: msdn.microsoft.com/en-us/library/aa371886%28v=vs.85%29.aspx. I would like to shorten the amount of time between consecutive checks on the context switches (make it less than a second). If anyone has any ideas as to how to do this, that'd be great.

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