计数器、WMI

获取设备的内存信息，如系统可用运行内存：

 1     public static async Task<double> GetMemoryAvailableAsync(FileSizeUnit fileSizeUnit = FileSizeUnit.GB)
 2     {
 3         return await Task.Run(() =>
 4         {
 5             using var managementClass = new ManagementClass("Win32_PerfFormattedData_PerfOS_Memory");
 6             using var instances = managementClass.GetInstances();
 7             double available = 0;
 8             foreach (var mo in instances)
 9             {
10                 //AvailableMBytes单位是MB
11                 var size = long.Parse(mo.Properties["AvailableMBytes"].Value.ToString()) * 1024 * 1024;
12                 available += size.ConvertTo(fileSizeUnit);
13             }
14 
15             return available;
16         });
17     }

以上是ManagementClass方式实现，还有ManagementObjectSearcher，都是WMI检索查询。

WMI查询比较慢，上面一段耗时在200ms+。

还有一种用的较多的，PerformanceCounter性能计数器，以CPU获取为例：

 1     public static async Task<double> GetUsageByCounterAsync()
 2     {
 3         //CPU计数器 
 4         using var pcCpuUsage = new PerformanceCounter("Processor", "% Processor Time", "_Total") { MachineName = "." };
 5         // NextValue首次会返回0，所以需要加个延时下次再获取值
 6         pcCpuUsage.NextValue();
 7         await Task.Delay(TimeSpan.FromMilliseconds(500));
 8         var cpuUsed = pcCpuUsage.NextValue();
 9         return cpuUsed;
10     }

性能计数器，也有一定的耗时40ms以上。另外因为它实现方式，初始化后无法第一次获取到真正数值，需要间隔一段时间再去拿。所以此方案实际耗时挺高

WMI、性能计数器，昨天遇到了使用异常：

 

看源码，计数器是注册表PerformanceData位置损坏了，而Management是IWbemServices获取状态码ErrorCode异常。

PerformanceCounter是WMI，而WMI是基于WBEM协议实现的，所以我理解成上面的异常其实是一类问题。

官网有对此类异常有一些描述：重新生成性能计数器库值 - Windows Server | Microsoft Learn 

所以基于PerformanceCounter、ManagementClass以及ManagementObjectSearcher的实现，有一定风险。

kernel32

kernel32下有个函数可以获取内存状态

1     [DllImport("kernel32.dll")]
2     [return: MarshalAs(UnmanagedType.Bool)]
3     static extern bool GlobalMemoryStatusEx(ref MEMORYINFO mi);

以下是获取可用运行内存的实现：

    //Define the information structure of memory
    [StructLayout(LayoutKind.Sequential)]
    struct MEMORYINFO
    {
        public uint dwLength; //Current structure size
        public uint dwMemoryLoad; //Current memory utilization
        public ulong ullTotalPhys; //Total physical memory size
        public ulong ullAvailPhys; //Available physical memory size
        public ulong ullTotalPageFile; //Total Exchange File Size
        public ulong ullAvailPageFile; //Total Exchange File Size
        public ulong ullTotalVirtual; //Total virtual memory size
        public ulong ullAvailVirtual; //Available virtual memory size
        public ulong ullAvailExtendedVirtual; //Keep this value always zero
    }

    /// <summary>
    /// Get the current memory usage
    /// </summary>
    /// <returns></returns>
    private static MEMORYINFO GetMemoryStatus()
    {
        MEMORYINFO memoryInfo = new MEMORYINFO();
        memoryInfo.dwLength = (uint)System.Runtime.InteropServices.Marshal.SizeOf(memoryInfo);
        GlobalMemoryStatusEx(ref memoryInfo);
        return memoryInfo;
    }
    /// <summary>
    /// 获取系统可用运行内存
    /// </summary>
    /// <param name="fileSizeUnit">默认单位GB</param>
    /// <returns></returns>
    public static double GetMemoryAvailable(FileSizeUnit fileSizeUnit = FileSizeUnit.GB)
    {
        var memoryStatus = GetMemoryStatus();
        var memoryAvailable = ((long)memoryStatus.ullAvailPhys).ConvertTo(fileSizeUnit);
        return memoryAvailable;
    }

上述方式，获取速度超快，几乎不耗时。

通过Kernel32-GetSystemTimes方式，获取CPU信息（CPU比例计算逻辑，代码略多点）：

 1     /// <summary>
 2     /// 获取CPU占用率/使用率（单位：%）
 3     /// </summary>
 4     /// <returns></returns>
 5     public static async Task<double> GetUsageByKernelAsync()
 6     {
 7         long idleTime1 = 0;
 8         long kernelTime1 = 0;
 9         long userTime1 = 0;
10         if (GetSystemTimes(out var lpIdleTime, out var lpKernelTime, out var lpUserTime))
11         {
12             idleTime1 = lpIdleTime;
13             kernelTime1 = lpKernelTime;
14             userTime1 = lpUserTime;
15         }
16         //添加俩次获取CPU信息的间隔
17         await Task.Delay(TimeSpan.FromSeconds(0.5));
18         long idleTime2 = 0;
19         long kernelTime2 = 0;
20         long userTime2 = 0;
21         if (GetSystemTimes(out var lpIdleTime2, out var lpKernelTime2, out var lpUserTime2))
22         {
23             idleTime2 = lpIdleTime2;
24             kernelTime2 = lpKernelTime2;
25             userTime2 = lpUserTime2;
26         }
27         //分别获取到用户时间、内核时间、空闲时间
28         var userTime = userTime2 - userTime1;
29         var kernelTime = kernelTime2 - kernelTime1;
30         var idleTime = idleTime2 - idleTime1;
31         //计算Cpu占用率。计算公式：用户时间+内核时间-空闲时间/用户时间+内核时间
32         var systemTotal = kernelTime + userTime;
33         var cpu = (systemTotal - idleTime) * 10000 / systemTotal;
34         return cpu / 100.0;
35     }
36 
37     /// <summary>
38     /// 获取系统CPU时间数据
39     /// </summary>
40     /// <param name="lpIdleTime">空闲时间</param>
41     /// <param name="lpKernelTime">内核时间</param>
42     /// <param name="lpUserTime">用户时间</param>
43     /// <returns></returns>
44     [DllImport("kernel32.dll", SetLastError = true)]
45     static extern bool GetSystemTimes(out long lpIdleTime, out long lpKernelTime, out long lpUserTime);

另外，也有一种途径可以获取到内存信息，引用程序集Microsoft.VisualBasic，Microsoft.VisualBasic.Devices下有个ComputerInfo类

var physicalMemory = new Microsoft.VisualBasic.Devices.ComputerInfo().AvailablePhysicalMemory;

可以拿到可用内存、总内存，不过CPU信息是没有的。

ComputerInfo的内部源码，我标注了下：

所以ComputerInfo，也是基于GlobalMemoryStatusEx函数做了封装，大家可以直接用。

 

关键字：【Kernek32-GlobalMemoryStatusEx】【Kernek32-GetSystemTimes】

参考列表：