cpu_features.NET

.NET version of google/cpu_features for getting cpu info at runtime.

Table of Contents

• Design Rationale
• Code samples
• Running sample code
• What's supported
• License

Design Rationale

• .NET Standard 1.1
• Simple to use. See the snippets below for examples.
• cpu_features.NET is suitable for implementing lib functions.

Code samples

Checking features at runtime

Here's a simple example that executes a codepath if the CPU supports SSE4A instruction sets:

using System;
using CpuFeaturesDotNet.X86;

namespace CpuFeaturesDotNet.Samples
{
    public class Program
    {
        public static void Main(string[] args) 
        {
            X86Info x86Info = X86Info.GetX86Info();
            bool sse4a = x86Info.Features.IsSupportedSSE4A;
            if (sse4a) 
            {
                // Run optimized code.
            }
            else 
            {
                // Run standard code.
            }
        }
    }
}

Caching for faster evaluation of complex checks

If you wish, you can read all the features at once into a global variable, and then query for the specific features you care about.

using System;
using CpuFeaturesDotNet.X86;

namespace CpuFeaturesDotNet.Samples
{
    public class Program
    {
        public static X86Info X86Info = X86Info.GetX86Info();
        
        public static void Main(string[] args) 
        {
            X86Microarchitecture uarch = X86Info.GetX86Microarchitecture(info);
            bool hasFastAvx = info.Features.IsSupportedAVX && uarch != X86Microarchitecture.INTEL_SANDYBRIDGE;
        }
    }
}

Rejecting poor hardware implementations based on microarchitecture

On x86, the first incarnation of a feature in a microarchitecture might not be the most efficient (e.g. AVX on Sandy Bridge). We provide a function to retrieve the underlying microarchitecture so you can decide whether to use it.

Below, hasFastAvx is set to 1 if the CPU supports the AVX instruction set—but only if it's not Sandy Bridge.

using System;
using CpuFeaturesDotNet.X86;

namespace CpuFeaturesDotNet.Samples
{
    public class Program
    {
        public static void Main(string[] args) 
        {
            X86Info info = X86Info.GetX86Info();
            X86Microarchitecture uarch = X86Info.GetX86Microarchitecture(info);
            bool hasFastAvx = info.Features.IsSupportedAVX && uarch != X86Microarchitecture.INTEL_SANDYBRIDGE;
        }
    }
}

This feature is currently available only for x86 microarchitectures.

Running sample code

Use CpuFeaturesDotNet.Samples for detection your CPU.

CpuFeaturesDotNet.Samples.CpuFeaturesListX64.StartRunner

{
  "Features": {
    "IsSupportedFPU": true,
    "IsSupportedTSC": true,
    "IsSupportedCX8": true,
    "IsSupportedCLFSH": true,
    "IsSupportedMMX": true,
    "IsSupportedAES": true,
    "IsSupportedERMS": true,
    "IsSupportedF16C": true,
    "IsSupportedFMA4": false,
    "IsSupportedFMA3": true,
    "IsSupportedVAES": false,
    "IsSupportedVPCLMULQDQ": false,
    "IsSupportedBMI1": true,
    "IsSupportedHLE": false,
    "IsSupportedBMI2": true,
    "IsSupportedRTM": false,
    "IsSupportedRDSEED": true,
    "IsSupportedCLFLUSHOPT": true,
    "IsSupportedCLWB": false,
    "IsSupportedSSE": true,
    "IsSupportedSSE2": true,
    "IsSupportedSSE3": true,
    "IsSupportedSSSE3": true,
    "IsSupportedSSE4_1": true,
    "IsSupportedSSE4_2": true,
    "IsSupportedSSE4A": false,
    "IsSupportedAVX": true,
    "IsSupportedAVX2": true,
    "IsSupportedAVX512F": false,
    "IsSupportedAVX512CD": false,
    "IsSupportedAVX512ER": false,
    "IsSupportedAVX512PF": false,
    "IsSupportedAVX512BW": false,
    "IsSupportedAVX512DQ": false,
    "IsSupportedAVX512VL": false,
    "IsSupportedAVX512IFMA": false,
    "IsSupportedAVX512VBMI": false,
    "IsSupportedAVX512VBMI2": false,
    "IsSupportedAVX512VNNI": false,
    "IsSupportedAVX512BITALG": false,
    "IsSupportedAVX512VPOPCNTDQ": false,
    "IsSupportedAVX512_4VNNIW": false,
    "IsSupportedAVX512_4VBMI2": false,
    "IsSupportedAVX512_SECOND_FMA": false,
    "IsSupportedAVX512_4FMAPS": false,
    "IsSupportedAVX512_BF16": false,
    "IsSupportedAVX512_VP2INTERSECT": false,
    "IsSupportedAMX_BF16": false,
    "IsSupportedAMX_TILE": false,
    "IsSupportedAMX_INT8": false,
    "IsSupportedPCLMULQDQ": true,
    "IsSupportedSMX": false,
    "IsSupportedSGX": false,
    "IsSupportedCX16": true,
    "IsSupportedSHA": false,
    "IsSupportedDPOPCNT": true,
    "IsSupportedDMOVBE": true,
    "IsSupportedDRDRND": true,
    "IsSupportedDCA": false,
    "IsSupportedSS": true,
    "IsSupportedADX": true
  },
  "Family": 6,
  "Model": 142,
  "Stepping": 10,
  "Vendor": "GenuineIntel",
  "BrandString": "Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz"
}
{
  "Size": 4,
  "Levels": [
    {
      "Level": 1,
      "CacheType": "CPU_FEATURE_CACHE_DATA",
      "CacheSize": 32768,
      "Ways": 8,
      "LineSize": 64,
      "TlbEntries": 64,
      "Partitioning": 1
    },
    {
      "Level": 1,
      "CacheType": "CPU_FEATURE_CACHE_INSTRUCTION",
      "CacheSize": 32768,
      "Ways": 8,
      "LineSize": 64,
      "TlbEntries": 64,
      "Partitioning": 1
    },
    {
      "Level": 2,
      "CacheType": "CPU_FEATURE_CACHE_UNIFIED",
      "CacheSize": 262144,
      "Ways": 4,
      "LineSize": 64,
      "TlbEntries": 1024,
      "Partitioning": 1
    },
    {
      "Level": 3,
      "CacheType": "CPU_FEATURE_CACHE_UNIFIED",
      "CacheSize": 6291456,
      "Ways": 12,
      "LineSize": 64,
      "TlbEntries": 8192,
      "Partitioning": 1
    },
    {
      "Level": 0,
      "CacheType": "CPU_FEATURE_CACHE_NULL",
      "CacheSize": 0,
      "Ways": 0,
      "LineSize": 0,
      "TlbEntries": 0,
      "Partitioning": 0
    },
    {
      "Level": 0,
      "CacheType": "CPU_FEATURE_CACHE_NULL",
      "CacheSize": 0,
      "Ways": 0,
      "LineSize": 0,
      "TlbEntries": 0,
      "Partitioning": 0
    },
    {
      "Level": 0,
      "CacheType": "CPU_FEATURE_CACHE_NULL",
      "CacheSize": 0,
      "Ways": 0,
      "LineSize": 0,
      "TlbEntries": 0,
      "Partitioning": 0
    },
    {
      "Level": 0,
      "CacheType": "CPU_FEATURE_CACHE_NULL",
      "CacheSize": 0,
      "Ways": 0,
      "LineSize": 0,
      "TlbEntries": 0,
      "Partitioning": 0
    },
    {
      "Level": 0,
      "CacheType": "CPU_FEATURE_CACHE_NULL",
      "CacheSize": 0,
      "Ways": 0,
      "LineSize": 0,
      "TlbEntries": 0,
      "Partitioning": 0
    },
    {
      "Level": 0,
      "CacheType": "CPU_FEATURE_CACHE_NULL",
      "CacheSize": 0,
      "Ways": 0,
      "LineSize": 0,
      "TlbEntries": 0,
      "Partitioning": 0
    }
  ]
}

Note: Before run CpuFeaturesDotNet.Samples you need build project through cmake.

cmake -S. -Bcmake-build-release -DCMAKE_BUILD_TYPE=Release
cmake --build cmake-build-release --target all -v

Detailed instruction see Local-Nuget-package-building

What's supported

Runtime / OS	x86³	ARM	AArch64
.NET Framework Windows	in progress	N/A	N/A
.NET Core Windows	yes²	not yet	not yet
.NET Core Linux	yes²	in progress	in progress
.NET Core macOS	yes²	not yet	not yet
.NET Core FreeBSD	not yet	not yet	not yet
Mono Windows	not yet	not yet	not yet
Mono Linux	not yet	not yet	not yet
Mono macOS	not yet	N/A	not yet
Mono FreeBSD	not yet	not yet	not yet
Mono Android	not yet	not yet	not yet
Mono iOS	N/A	N/A	not yet

1. Features revealed from Linux. We gather data from several sources depending on availability:
   • from glibc's getauxval
   • by parsing /proc/self/auxv
   • by parsing /proc/cpuinfo
2. Features revealed from CPU. features are retrieved by using the cpuid instruction.
3. Microarchitecture detection. On x86 some features are not always implemented efficiently in hardware (e.g. AVX on Sandybridge). Exposing the microarchitecture allows the client to reject particular microarchitectures.

License

The cpu_features.NET library is licensed under the terms of the Apache license. See LICENSE for more information.