cpuinfo

CPU INFOrmation library

cpuinfo is a library to detect essential for performance optimization information about host CPU.

Features

• Cross-platform availability:
  • Linux, Windows, macOS, Android, iOS and FreeBSD operating systems
  • x86, x86-64, ARM, and ARM64 architectures
• Modern C/C++ interface
  • Thread-safe
  • No memory allocation after initialization
  • No exceptions thrown
• Detection of supported instruction sets, up to AVX512 (x86) and ARMv8.3 extensions
• Detection of SoC and core information:
  • Processor (SoC) name
  • Vendor and microarchitecture for each CPU core
  • ID (MIDR on ARM, CPUID leaf 1 EAX value on x86) for each CPU core
• Detection of cache information:
  • Cache type (instruction/data/unified), size and line size
  • Cache associativity
  • Cores and logical processors (hyper-threads) sharing the cache
• Detection of topology information (relative between logical processors, cores, and processor packages)
• Well-tested production-quality code:
  • 60+ mock tests based on data from real devices
  • Includes work-arounds for common bugs in hardware and OS kernels
  • Supports systems with heterogenous cores, such as big.LITTLE and Max.Med.Min
• Permissive open-source license (Simplified BSD)

Examples

Log processor name:

cpuinfo_initialize();
printf("Running on %s CPU\n", cpuinfo_get_package(0)->name);

Detect if target is a 32-bit or 64-bit ARM system:

#if CPUINFO_ARCH_ARM || CPUINFO_ARCH_ARM64
    /* 32-bit ARM-specific code here */
#endif

Check if the host CPU supports ARM NEON

cpuinfo_initialize();
if (cpuinfo_has_arm_neon()) {
    neon_implementation(arguments);
}

Check if the host CPU supports x86 AVX

cpuinfo_initialize();
if (cpuinfo_has_x86_avx()) {
    avx_implementation(arguments);
}

Check if the thread runs on a Cortex-A53 core

cpuinfo_initialize();
switch (cpuinfo_get_current_core()->uarch) {
    case cpuinfo_uarch_cortex_a53:
        cortex_a53_implementation(arguments);
        break;
    default:
        generic_implementation(arguments);
        break;
}

Get the size of level 1 data cache on the fastest core in the processor (e.g. big core in big.LITTLE ARM systems):

cpuinfo_initialize();
const size_t l1_size = cpuinfo_get_processor(0)->cache.l1d->size;

Pin thread to cores sharing L2 cache with the current core (Linux or Android)

cpuinfo_initialize();
cpu_set_t cpu_set;
CPU_ZERO(&cpu_set);
const struct cpuinfo_cache* current_l2 = cpuinfo_get_current_processor()->cache.l2;
for (uint32_t i = 0; i < current_l2->processor_count; i++) {
    CPU_SET(cpuinfo_get_processor(current_l2->processor_start + i)->linux_id, &cpu_set);
}
pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpu_set);

Use via pkg-config

If you would like to provide your project’s build environment with the necessary compiler and linker flags in a portable manner, the library by default when built enables CPUINFO_BUILD_PKG_CONFIG and will generate a pkg-config manifest (libcpuinfo.pc). Here are several examples of how to use it:

Command Line

If you used your distro’s package manager to install the library, you can verify that it is available to your build environment like so:

$ pkg-config --cflags --libs libcpuinfo
-I/usr/include/x86_64-linux-gnu/ -L/lib/x86_64-linux-gnu/ -lcpuinfo

If you have installed the library from source into a non-standard prefix, pkg-config may need help finding it:

$ PKG_CONFIG_PATH="/home/me/projects/cpuinfo/prefix/lib/pkgconfig/:$PKG_CONFIG_PATH" pkg-config --cflags --libs libcpuinfo
-I/home/me/projects/cpuinfo/prefix/include -L/home/me/projects/cpuinfo/prefix/lib -lcpuinfo

GNU Autotools

To use with the GNU Autotools include the following snippet in your project’s configure.ac:

# CPU INFOrmation library...
PKG_CHECK_MODULES(
    [libcpuinfo], [libcpuinfo], [],
    [AC_MSG_ERROR([libcpuinfo missing...])])
YOURPROJECT_CXXFLAGS="$YOURPROJECT_CXXFLAGS $libcpuinfo_CFLAGS"
YOURPROJECT_LIBS="$YOURPROJECT_LIBS $libcpuinfo_LIBS"

Meson

To use with Meson you just need to add dependency('libcpuinfo') as a dependency for your executable.

project(
    'MyCpuInfoProject',
    'cpp',
    meson_version: '>=0.55.0'
)

executable(
    'MyCpuInfoExecutable',
    sources: 'main.cpp',
    dependencies: dependency('libcpuinfo')
)

Bazel

This project can be built using Bazel.

You can also use this library as a dependency to your Bazel project. Add to your MODULE.bazel file:

# fetch cpuinfo from Bazel Central Registry: https://registry.bazel.build/modules/cpuinfo
bazel_dep(name = "cpuinfo", version = "0.0.0-20250925-877328f")

# Optional: Override it with some specific commit hash
git_override(
    module_name = "cpuinfo",
    commit = "<replace_with_commit_hash>"
    remote = "https://github.com/pytorch/cpuinfo.git",
)

And to your BUILD file:

cc_binary(
    name = "cpuinfo_test",
    srcs = [
        # ...
    ],
    deps = [
        "@cpuinfo",
    ],
)

CMake

To use with CMake use the FindPkgConfig module. Here is an example:

cmake_minimum_required(VERSION 3.6)
project("MyCpuInfoProject")

find_package(PkgConfig)
pkg_check_modules(CpuInfo REQUIRED IMPORTED_TARGET libcpuinfo)

add_executable(${PROJECT_NAME} main.cpp)
target_link_libraries(${PROJECT_NAME} PkgConfig::CpuInfo)

Makefile

To use within a vanilla makefile, you can call pkg-config directly to supply compiler and linker flags using shell substitution.

CFLAGS=-g3 -Wall -Wextra -Werror ...
LDFLAGS=-lfoo ...
...
CFLAGS+= $(pkg-config --cflags libcpuinfo)
LDFLAGS+= $(pkg-config --libs libcpuinfo)

Exposed information

• Processor (SoC) name
• Microarchitecture
• Usable instruction sets
• CPU frequency
• Cache
  • Size
  • Associativity
  • Line size
  • Number of partitions
  • Flags (unified, inclusive, complex hash function)
  • Topology (logical processors that share this cache level)
• TLB
  • Number of entries
  • Associativity
  • Covered page types (instruction, data)
  • Covered page sizes
• Topology information
  • Logical processors
  • Cores
  • Packages (sockets)

Supported environments:

• Android
  • x86 ABI
  • x86_64 ABI
  • armeabi ABI
  • armeabiv7-a ABI
  • arm64-v8a ABI
  • mips ABI
  • mips64 ABI
• Linux
  • x86
  • x86-64
  • 32-bit ARM (ARMv5T and later)
  • ARM64
  • PowerPC64
• iOS
  • x86 (iPhone simulator)
  • x86-64 (iPhone simulator)
  • ARMv7
  • ARM64
• macOS
  • x86
  • x86-64
  • ARM64 (Apple silicon)
• Windows
  • x86
  • x86-64
  • arm64
• FreeBSD
  • x86-64

Methods

• Processor (SoC) name detection
  • Using CPUID leaves 0x80000002–0x80000004 on x86/x86-64
  • Using /proc/cpuinfo on ARM
  • Using ro.chipname, ro.board.platform, ro.product.board, ro.mediatek.platform, ro.arch properties (Android)
  • Using kernel log (dmesg) on ARM Linux
  • Using Windows registry on ARM64 Windows
• Vendor and microarchitecture detection
  • Intel-designed x86/x86-64 cores (up to Sunny Cove, Goldmont Plus, and Knights Mill)
  • AMD-designed x86/x86-64 cores (up to Puma/Jaguar and Zen 2)
  • VIA-designed x86/x86-64 cores
  • Other x86 cores (DM&P, RDC, Transmeta, Cyrix, Rise)
  • ARM-designed ARM cores (up to Cortex-A55, Cortex-A77, and Neoverse E1/V1/N2/V2/V3/V3AE)
  • Qualcomm-designed ARM cores (Scorpion, Krait, and Kryo)
  • Nvidia-designed ARM cores (Denver and Carmel)
  • Samsung-designed ARM cores (Exynos)
  • Intel-designed ARM cores (XScale up to 3rd-gen)
  • Apple-designed ARM cores (up to Lightning and Thunder)
  • Cavium-designed ARM cores (ThunderX)
  • AppliedMicro-designed ARM cores (X-Gene)
• Instruction set detection
  • Using CPUID (x86/x86-64)
  • Using /proc/cpuinfo on 32-bit ARM EABI (Linux)
  • Using microarchitecture heuristics on (32-bit ARM)
  • Using FPSID and WCID registers (32-bit ARM)
  • Using getauxval (Linux/ARM)
  • Using /proc/self/auxv (Android/ARM)
  • Using instruction probing on ARM (Linux)
  • Using CPUID registers on ARM64 (Linux)
  • Using IsProcessorFeaturePresent on ARM64 Windows
• Cache detection
  • Using CPUID leaf 0x00000002 (x86/x86-64)
  • Using CPUID leaf 0x00000004 (non-AMD x86/x86-64)
  • Using CPUID leaves 0x80000005-0x80000006 (AMD x86/x86-64)
  • Using CPUID leaf 0x8000001D (AMD x86/x86-64)
  • Using /proc/cpuinfo (Linux/pre-ARMv7)
  • Using microarchitecture heuristics (ARM)
  • Using chipset name (ARM)
  • Using sysctlbyname (Mach)
  • Using sysfs typology directories (ARM/Linux)
  • Using sysfs cache directories (Linux)
  • Using GetLogicalProcessorInformationEx on ARM64 Windows
• TLB detection
  • Using CPUID leaf 0x00000002 (x86/x86-64)
  • Using CPUID leaves 0x80000005-0x80000006 and 0x80000019 (AMD x86/x86-64)
  • Using microarchitecture heuristics (ARM)
• Topology detection
  • Using CPUID leaf 0x00000001 on x86/x86-64 (legacy APIC ID)
  • Using CPUID leaf 0x0000000B on x86/x86-64 (Intel APIC ID)
  • Using CPUID leaf 0x8000001E on x86/x86-64 (AMD APIC ID)
  • Using /proc/cpuinfo (Linux)
  • Using host_info (Mach)
  • Using GetLogicalProcessorInformationEx (Windows)
  • Using sysfs (Linux)
  • Using chipset name (ARM/Linux)