aosp12/external/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, and iOS 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 support 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);

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
• OS X
  • x86
  • x86-64
• Windows
  • x86
  • 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
• 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/N1)
  • 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)
• 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)
• 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)