Add support for Linux cgrpoup v2, issue-4885

src/Libraries/Microsoft.Extensions.Diagnostics.ResourceMonitoring/Linux/ILinuxUtilizationParser.cs

@@ -0,0 +1,69 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.Extensions.Diagnostics.ResourceMonitoring.Linux;
+
+/// <summary>
+/// An interface to be implemented by a parser that reads files and extracts resource utilization data from them.
+/// For both versions of cgroup controllers, the parser reads files from the /sys/fs/cgroup directory.
+/// </summary>
+internal interface ILinuxUtilizationParser
+{
+    /// <summary>
+    /// Reads file /sys/fs/cgroup/memory.max, which  is used to check the maximum amount of memory that can be used by a cgroup.
+    /// It is part of the cgroup v2 memory controller.
+    /// </summary>
+    /// <returns>maybeMemory.</returns>
+    ulong GetAvailableMemoryInBytes();
+
+    /// <summary>
+    /// Reads the file /sys/fs/cgroup/cpu.stat, which is part of the cgroup v2 CPU controller.
+    /// It provides statistics about the CPU usage of a cgroup.
+    /// </summary>
+    /// <returns>nanoseconds.</returns>
+    long GetCgroupCpuUsageInNanoseconds();
+
+    /// <summary>
+    /// Reads the file /sys/fs/cgroup/cpu.max, which is part of the cgroup v2 CPU controller.
+    /// It is used to set the maximum amount of CPU time that can be used by a cgroup.
+    /// The file contains two fields, separated by a space.
+    /// The first field is the quota, which specifies the maximum amount of CPU time (in microseconds) that can be used by the cgroup during one period.
+    /// The second value is the period, which specifies the length of a period in microseconds.
+    /// </summary>
+    /// <returns>cpuUnits.</returns>
+    float GetCgroupLimitedCpus();
+
+    /// <summary>
+    /// Reads the file /proc/stat, which  provides information about the system’s memory usage.
+    /// It contains information about the total amount of installed memory, the amount of free and used memory, and the amount of memory used by the kernel and buffers/cache.
+    /// </summary>
+    /// <returns>memory.</returns>
+    ulong GetHostAvailableMemory();
+
+    /// <summary>
+    /// Reads the file /sys/fs/cgroup/cpuset.cpus.effective, which is part of the cgroup v2 cpuset controller.
+    /// It shows the effective cpus that the cgroup can use. 
+    /// </summary>
+    /// <returns>cpuCount.</returns>
+    float GetHostCpuCount();
+
+    /// <summary>
+    /// Reads the file /sys/fs/cgroup/cpu.stat, which is part of the cgroup v2 CPU controller.
+    /// It provides statistics about the CPU usage of a cgroup.
+    /// The file contains several fields, including usage_usec, which shows the total CPU time (in microseconds).
+    /// </summary>
+    /// <returns>total / (double)_userHz * NanosecondsInSecond.</returns>
+    long GetHostCpuUsageInNanoseconds();
+
+    /// <summary>
+    /// Reads the file /sys/fs/cgroup/memory.current, which is a file that contains the current memory usage of a cgroup in bytes.
+    /// </summary>
+    /// <returns>memoryUsage.</returns>
+    ulong GetMemoryUsageInBytes();
+
+    /// <summary>
+    /// Reads the file /sys/fs/cgroup/cpu.weight. And calculates the Pod CPU Request in millicores.
+    /// </summary>
+    /// <returns>cpuPodRequest.</returns>
+    float GetCgroupRequestCpu();
+}

src/Libraries/Microsoft.Extensions.Diagnostics.ResourceMonitoring/Linux/LinuxUtilizationParser.cs

@@ -14,8 +14,10 @@ namespace Microsoft.Extensions.Diagnostics.ResourceMonitoring.Linux;
 /// This class is not thread safe.
 /// When the same instance is called by multiple threads it may return corrupted data.
 /// </remarks>
-internal sealed class LinuxUtilizationParser
+internal sealed class LinuxUtilizationParser : ILinuxUtilizationParser
 {
+    private const float CpuShares = 1024;
+
     /// <remarks>
     /// File contains the amount of CPU time (in microseconds) available to the group during each accounting period.
     /// </remarks>
@@ -76,6 +78,11 @@ internal sealed class LinuxUtilizationParser
     /// </remarks>
     private static readonly FileInfo _cpuacctUsage = new("/sys/fs/cgroup/cpuacct/cpuacct.usage");
 
+    /// <summary>
+    /// CPU weights, also known as shares in cgroup v1, is used for resource allocation.
+    /// </summary>
+    private static readonly FileInfo _cpuPodWeight = new("/sys/fs/cgroup/cpu/cpu.shares");
+
     private readonly IFileSystem _fileSystem;
     private readonly long _userHz;
     private readonly BufferWriter<char> _buffer = new();
@@ -160,6 +167,17 @@ public float GetCgroupLimitedCpus()
         return GetHostCpuCount();
     }
 
+    public float GetCgroupRequestCpu()
+    {
+        if (TryGetCgroupRequestCpu(_fileSystem, out var cpuUnits))
+        {
+            return cpuUnits;
+        }
+
+        // If we can't read the CPU weight, we assume that the pod request is 1 core.
+        return 1;
+    }
+
     public ulong GetAvailableMemoryInBytes()
     {
         const long UnsetCgroupMemoryLimit = 9_223_372_036_854_771_712;
@@ -425,4 +443,38 @@ private bool TryGetCpuUnitsFromCgroups(IFileSystem fileSystem, out float cpuUnit
         cpuUnits = (float)quota / period;
         return true;
     }
+
+    /// <summary>
+    /// In cgroup v1 the CPU shares is used to determine the CPU allocation.
+    /// in cgroup v2 the CPU weight is used to determine the CPU allocation.
+    /// To calculete CPU request in cgroup v2 we need to read the CPU weight and convert it to CPU shares.
+    /// But for cgroup v1 we can read the CPU shares directly from the file.
+    /// 1024 equals 1 CPU core.
+    /// In cgroup v1 on some systems the location of the CPU shares file is different.
+    /// </summary>
+    private bool TryGetCgroupRequestCpu(IFileSystem fileSystem, out float cpuUnits)
+    {
+        if (!_cpuPodWeight.Exists)
+        {
+            cpuUnits = 1;
+            return false;
+        }
+
+        fileSystem.ReadFirstLine(_cpuPodWeight, _buffer);
+        var cpuPodWeightBuffer = _buffer.WrittenSpan;
+        _ = GetNextNumber(cpuPodWeightBuffer, out var cpuPodWeight);
+
+        if (cpuPodWeightBuffer.IsEmpty || (cpuPodWeightBuffer.Length == 2 && cpuPodWeightBuffer[0] == '-' && cpuPodWeightBuffer[1] == '1'))
+        {
+            _buffer.Reset();
+            Throw.InvalidOperationException($"Could not parse '{_cpuPodWeight}' content. Expected to find CPU weight but got '{new string(cpuPodWeightBuffer)}' instead.");
+            cpuUnits = -1;
+            return false;
+        }
+
+        _buffer.Reset();
+        var result = cpuPodWeight / CpuShares;
+        cpuUnits = result;
+        return true;
+    }
 }