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- // Copyright (c) 2012 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/cpu.h"
- #include <inttypes.h>
- #include <limits.h>
- #include <stddef.h>
- #include <stdint.h>
- #include <string.h>
- #include <algorithm>
- #include <sstream>
- #include <utility>
- #include "base/no_destructor.h"
- #include "build/build_config.h"
- #if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID) || \
- BUILDFLAG(IS_AIX)
- #include "base/containers/flat_set.h"
- #include "base/files/file_util.h"
- #include "base/format_macros.h"
- #include "base/notreached.h"
- #include "base/process/internal_linux.h"
- #include "base/strings/string_number_conversions.h"
- #include "base/strings/string_util.h"
- #include "base/strings/stringprintf.h"
- #include "base/system/sys_info.h"
- #include "base/threading/thread_restrictions.h"
- #endif
- #if defined(ARCH_CPU_ARM_FAMILY) && \
- (BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS))
- #include <asm/hwcap.h>
- #include <sys/auxv.h>
- #include "base/files/file_util.h"
- #include "base/numerics/checked_math.h"
- #include "base/ranges/algorithm.h"
- #include "base/strings/string_split.h"
- #include "base/strings/string_util.h"
- // Temporary definitions until a new hwcap.h is pulled in everywhere.
- // https://crbug.com/1265965
- #ifndef HWCAP2_MTE
- #define HWCAP2_MTE (1 << 18)
- #define HWCAP2_BTI (1 << 17)
- #endif
- struct ProcCpuInfo {
- std::string brand;
- uint8_t implementer = 0;
- uint32_t part_number = 0;
- };
- #endif
- #if defined(ARCH_CPU_X86_FAMILY)
- #if defined(COMPILER_MSVC)
- #include <intrin.h>
- #include <immintrin.h> // For _xgetbv()
- #endif
- #endif
- namespace base {
- #if defined(ARCH_CPU_X86_FAMILY)
- namespace internal {
- X86ModelInfo ComputeX86FamilyAndModel(const std::string& vendor,
- int signature) {
- X86ModelInfo results;
- results.family = (signature >> 8) & 0xf;
- results.model = (signature >> 4) & 0xf;
- results.ext_family = 0;
- results.ext_model = 0;
- // The "Intel 64 and IA-32 Architectures Developer's Manual: Vol. 2A"
- // specifies the Extended Model is defined only when the Base Family is
- // 06h or 0Fh.
- // The "AMD CPUID Specification" specifies that the Extended Model is
- // defined only when Base Family is 0Fh.
- // Both manuals define the display model as
- // {ExtendedModel[3:0],BaseModel[3:0]} in that case.
- if (results.family == 0xf ||
- (results.family == 0x6 && vendor == "GenuineIntel")) {
- results.ext_model = (signature >> 16) & 0xf;
- results.model += results.ext_model << 4;
- }
- // Both the "Intel 64 and IA-32 Architectures Developer's Manual: Vol. 2A"
- // and the "AMD CPUID Specification" specify that the Extended Family is
- // defined only when the Base Family is 0Fh.
- // Both manuals define the display family as {0000b,BaseFamily[3:0]} +
- // ExtendedFamily[7:0] in that case.
- if (results.family == 0xf) {
- results.ext_family = (signature >> 20) & 0xff;
- results.family += results.ext_family;
- }
- return results;
- }
- } // namespace internal
- #endif // defined(ARCH_CPU_X86_FAMILY)
- CPU::CPU(bool require_branding) {
- Initialize(require_branding);
- }
- CPU::CPU() : CPU(true) {}
- CPU::CPU(CPU&&) = default;
- namespace {
- #if defined(ARCH_CPU_X86_FAMILY)
- #if !defined(COMPILER_MSVC)
- #if defined(__pic__) && defined(__i386__)
- void __cpuid(int cpu_info[4], int info_type) {
- __asm__ volatile(
- "mov %%ebx, %%edi\n"
- "cpuid\n"
- "xchg %%edi, %%ebx\n"
- : "=a"(cpu_info[0]), "=D"(cpu_info[1]), "=c"(cpu_info[2]),
- "=d"(cpu_info[3])
- : "a"(info_type), "c"(0));
- }
- #else
- void __cpuid(int cpu_info[4], int info_type) {
- __asm__ volatile("cpuid\n"
- : "=a"(cpu_info[0]), "=b"(cpu_info[1]), "=c"(cpu_info[2]),
- "=d"(cpu_info[3])
- : "a"(info_type), "c"(0));
- }
- #endif
- #endif // !defined(COMPILER_MSVC)
- // xgetbv returns the value of an Intel Extended Control Register (XCR).
- // Currently only XCR0 is defined by Intel so |xcr| should always be zero.
- uint64_t xgetbv(uint32_t xcr) {
- #if defined(COMPILER_MSVC)
- return _xgetbv(xcr);
- #else
- uint32_t eax, edx;
- __asm__ volatile (
- "xgetbv" : "=a"(eax), "=d"(edx) : "c"(xcr));
- return (static_cast<uint64_t>(edx) << 32) | eax;
- #endif // defined(COMPILER_MSVC)
- }
- #endif // ARCH_CPU_X86_FAMILY
- #if defined(ARCH_CPU_ARM_FAMILY) && \
- (BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS))
- StringPairs::const_iterator FindFirstProcCpuKey(const StringPairs& pairs,
- StringPiece key) {
- return ranges::find_if(pairs, [key](const StringPairs::value_type& pair) {
- return TrimWhitespaceASCII(pair.first, base::TRIM_ALL) == key;
- });
- }
- // Parses information about the ARM processor. Note that depending on the CPU
- // package, processor configuration, and/or kernel version, this may only
- // report information about the processor on which this thread is running. This
- // can happen on heterogeneous-processor SoCs like Snapdragon 808, which has 4
- // Cortex-A53 and 2 Cortex-A57. Unfortunately there is not a universally
- // reliable way to examine the CPU part information for all cores.
- const ProcCpuInfo& ParseProcCpu() {
- static const NoDestructor<ProcCpuInfo> info([]() {
- // This function finds the value from /proc/cpuinfo under the key "model
- // name" or "Processor". "model name" is used in Linux 3.8 and later (3.7
- // and later for arm64) and is shown once per CPU. "Processor" is used in
- // earler versions and is shown only once at the top of /proc/cpuinfo
- // regardless of the number CPUs.
- const char kModelNamePrefix[] = "model name";
- const char kProcessorPrefix[] = "Processor";
- std::string cpuinfo;
- ReadFileToString(FilePath("/proc/cpuinfo"), &cpuinfo);
- DCHECK(!cpuinfo.empty());
- ProcCpuInfo info;
- StringPairs pairs;
- if (!SplitStringIntoKeyValuePairs(cpuinfo, ':', '\n', &pairs)) {
- NOTREACHED();
- return info;
- }
- auto model_name = FindFirstProcCpuKey(pairs, kModelNamePrefix);
- if (model_name == pairs.end())
- model_name = FindFirstProcCpuKey(pairs, kProcessorPrefix);
- if (model_name != pairs.end()) {
- info.brand =
- std::string(TrimWhitespaceASCII(model_name->second, TRIM_ALL));
- }
- auto implementer_string = FindFirstProcCpuKey(pairs, "CPU implementer");
- if (implementer_string != pairs.end()) {
- // HexStringToUInt() handles the leading whitespace on the value.
- uint32_t implementer;
- HexStringToUInt(implementer_string->second, &implementer);
- if (!CheckedNumeric<uint32_t>(implementer)
- .AssignIfValid(&info.implementer)) {
- info.implementer = 0;
- }
- }
- auto part_number_string = FindFirstProcCpuKey(pairs, "CPU part");
- if (part_number_string != pairs.end())
- HexStringToUInt(part_number_string->second, &info.part_number);
- return info;
- }());
- return *info;
- }
- #endif // defined(ARCH_CPU_ARM_FAMILY) && (BUILDFLAG(IS_ANDROID) ||
- // BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS))
- } // namespace
- void CPU::Initialize(bool require_branding) {
- #if defined(ARCH_CPU_X86_FAMILY)
- int cpu_info[4] = {-1};
- // This array is used to temporarily hold the vendor name and then the brand
- // name. Thus it has to be big enough for both use cases. There are
- // static_asserts below for each of the use cases to make sure this array is
- // big enough.
- char cpu_string[sizeof(cpu_info) * 3 + 1];
- // __cpuid with an InfoType argument of 0 returns the number of
- // valid Ids in CPUInfo[0] and the CPU identification string in
- // the other three array elements. The CPU identification string is
- // not in linear order. The code below arranges the information
- // in a human readable form. The human readable order is CPUInfo[1] |
- // CPUInfo[3] | CPUInfo[2]. CPUInfo[2] and CPUInfo[3] are swapped
- // before using memcpy() to copy these three array elements to |cpu_string|.
- __cpuid(cpu_info, 0);
- int num_ids = cpu_info[0];
- std::swap(cpu_info[2], cpu_info[3]);
- static constexpr size_t kVendorNameSize = 3 * sizeof(cpu_info[1]);
- static_assert(kVendorNameSize < std::size(cpu_string),
- "cpu_string too small");
- memcpy(cpu_string, &cpu_info[1], kVendorNameSize);
- cpu_string[kVendorNameSize] = '\0';
- cpu_vendor_ = cpu_string;
- // Interpret CPU feature information.
- if (num_ids > 0) {
- int cpu_info7[4] = {0};
- __cpuid(cpu_info, 1);
- if (num_ids >= 7) {
- __cpuid(cpu_info7, 7);
- }
- signature_ = cpu_info[0];
- stepping_ = cpu_info[0] & 0xf;
- type_ = (cpu_info[0] >> 12) & 0x3;
- internal::X86ModelInfo results =
- internal::ComputeX86FamilyAndModel(cpu_vendor_, signature_);
- family_ = results.family;
- model_ = results.model;
- ext_family_ = results.ext_family;
- ext_model_ = results.ext_model;
- has_mmx_ = (cpu_info[3] & 0x00800000) != 0;
- has_sse_ = (cpu_info[3] & 0x02000000) != 0;
- has_sse2_ = (cpu_info[3] & 0x04000000) != 0;
- has_sse3_ = (cpu_info[2] & 0x00000001) != 0;
- has_ssse3_ = (cpu_info[2] & 0x00000200) != 0;
- has_sse41_ = (cpu_info[2] & 0x00080000) != 0;
- has_sse42_ = (cpu_info[2] & 0x00100000) != 0;
- has_popcnt_ = (cpu_info[2] & 0x00800000) != 0;
- // "Hypervisor Present Bit: Bit 31 of ECX of CPUID leaf 0x1."
- // See https://lwn.net/Articles/301888/
- // This is checking for any hypervisor. Hypervisors may choose not to
- // announce themselves. Hypervisors trap CPUID and sometimes return
- // different results to underlying hardware.
- is_running_in_vm_ = (static_cast<uint32_t>(cpu_info[2]) & 0x80000000) != 0;
- // AVX instructions will generate an illegal instruction exception unless
- // a) they are supported by the CPU,
- // b) XSAVE is supported by the CPU and
- // c) XSAVE is enabled by the kernel.
- // See http://software.intel.com/en-us/blogs/2011/04/14/is-avx-enabled
- //
- // In addition, we have observed some crashes with the xgetbv instruction
- // even after following Intel's example code. (See crbug.com/375968.)
- // Because of that, we also test the XSAVE bit because its description in
- // the CPUID documentation suggests that it signals xgetbv support.
- has_avx_ =
- (cpu_info[2] & 0x10000000) != 0 &&
- (cpu_info[2] & 0x04000000) != 0 /* XSAVE */ &&
- (cpu_info[2] & 0x08000000) != 0 /* OSXSAVE */ &&
- (xgetbv(0) & 6) == 6 /* XSAVE enabled by kernel */;
- has_aesni_ = (cpu_info[2] & 0x02000000) != 0;
- has_fma3_ = (cpu_info[2] & 0x00001000) != 0;
- has_avx2_ = has_avx_ && (cpu_info7[1] & 0x00000020) != 0;
- }
- // Get the brand string of the cpu.
- __cpuid(cpu_info, static_cast<int>(0x80000000));
- const uint32_t max_parameter = static_cast<uint32_t>(cpu_info[0]);
- static constexpr uint32_t kParameterStart = 0x80000002;
- static constexpr uint32_t kParameterEnd = 0x80000004;
- static constexpr uint32_t kParameterSize =
- kParameterEnd - kParameterStart + 1;
- static_assert(kParameterSize * sizeof(cpu_info) + 1 == std::size(cpu_string),
- "cpu_string has wrong size");
- if (max_parameter >= kParameterEnd) {
- size_t i = 0;
- for (uint32_t parameter = kParameterStart; parameter <= kParameterEnd;
- ++parameter) {
- __cpuid(cpu_info, static_cast<int>(parameter));
- memcpy(&cpu_string[i], cpu_info, sizeof(cpu_info));
- i += sizeof(cpu_info);
- }
- cpu_string[i] = '\0';
- cpu_brand_ = cpu_string;
- }
- static constexpr uint32_t kParameterContainingNonStopTimeStampCounter =
- 0x80000007;
- if (max_parameter >= kParameterContainingNonStopTimeStampCounter) {
- __cpuid(cpu_info,
- static_cast<int>(kParameterContainingNonStopTimeStampCounter));
- has_non_stop_time_stamp_counter_ = (cpu_info[3] & (1 << 8)) != 0;
- }
- if (!has_non_stop_time_stamp_counter_ && is_running_in_vm_) {
- int cpu_info_hv[4] = {};
- __cpuid(cpu_info_hv, 0x40000000);
- if (cpu_info_hv[1] == 0x7263694D && // Micr
- cpu_info_hv[2] == 0x666F736F && // osof
- cpu_info_hv[3] == 0x76482074) { // t Hv
- // If CPUID says we have a variant TSC and a hypervisor has identified
- // itself and the hypervisor says it is Microsoft Hyper-V, then treat
- // TSC as invariant.
- //
- // Microsoft Hyper-V hypervisor reports variant TSC as there are some
- // scenarios (eg. VM live migration) where the TSC is variant, but for
- // our purposes we can treat it as invariant.
- has_non_stop_time_stamp_counter_ = true;
- }
- }
- #elif defined(ARCH_CPU_ARM_FAMILY)
- #if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS)
- if (require_branding) {
- const ProcCpuInfo& info = ParseProcCpu();
- cpu_brand_ = info.brand;
- implementer_ = info.implementer;
- part_number_ = info.part_number;
- }
- #if defined(ARCH_CPU_ARM64)
- // Check for Armv8.5-A BTI/MTE support, exposed via HWCAP2
- unsigned long hwcap2 = getauxval(AT_HWCAP2);
- has_mte_ = hwcap2 & HWCAP2_MTE;
- has_bti_ = hwcap2 & HWCAP2_BTI;
- #endif
- #elif BUILDFLAG(IS_WIN)
- // Windows makes high-resolution thread timing information available in
- // user-space.
- has_non_stop_time_stamp_counter_ = true;
- #endif
- #endif
- }
- #if defined(ARCH_CPU_X86_FAMILY)
- CPU::IntelMicroArchitecture CPU::GetIntelMicroArchitecture() const {
- if (has_avx2()) return AVX2;
- if (has_fma3()) return FMA3;
- if (has_avx()) return AVX;
- if (has_sse42()) return SSE42;
- if (has_sse41()) return SSE41;
- if (has_ssse3()) return SSSE3;
- if (has_sse3()) return SSE3;
- if (has_sse2()) return SSE2;
- if (has_sse()) return SSE;
- return PENTIUM;
- }
- #endif
- #if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_ANDROID) || \
- BUILDFLAG(IS_AIX)
- namespace {
- constexpr char kTimeInStatePath[] =
- "/sys/devices/system/cpu/cpu%" PRIuS "/cpufreq/stats/time_in_state";
- constexpr char kPhysicalPackageIdPath[] =
- "/sys/devices/system/cpu/cpu%" PRIuS "/topology/physical_package_id";
- constexpr char kCoreIdleStateTimePath[] =
- "/sys/devices/system/cpu/cpu%" PRIuS "/cpuidle/state%d/time";
- bool SupportsTimeInState() {
- // Reading from time_in_state doesn't block (it amounts to reading a struct
- // from the cpufreq-stats kernel driver).
- ThreadRestrictions::ScopedAllowIO allow_io;
- // Check if the time_in_state path for the first core is readable.
- FilePath time_in_state_path(
- StringPrintf(kTimeInStatePath, /*core_index=*/size_t{0}));
- ScopedFILE file_stream(OpenFile(time_in_state_path, "rb"));
- return static_cast<bool>(file_stream);
- }
- bool ParseTimeInState(const std::string& content,
- CPU::CoreType core_type,
- size_t core_index,
- CPU::TimeInState& time_in_state) {
- const char* begin = content.data();
- size_t max_pos = content.size() - 1;
- // Example time_in_state content:
- // ---
- // 300000 1
- // 403200 0
- // 499200 15
- // ---
- // Iterate over the individual lines.
- for (size_t pos = 0; pos <= max_pos;) {
- int num_chars = 0;
- // Each line should have two integer fields, frequency (kHz) and time (in
- // jiffies), separated by a space, e.g. "2419200 132".
- uint64_t frequency;
- int64_t time;
- int matches = sscanf(begin + pos, "%" PRIu64 " %" PRId64 "\n%n", &frequency,
- &time, &num_chars);
- if (matches != 2)
- return false;
- // Skip zero-valued entries in the output list (no time spent at this
- // frequency).
- if (time > 0) {
- time_in_state.push_back({core_type, core_index, frequency,
- internal::ClockTicksToTimeDelta(time)});
- }
- // Advance line.
- DCHECK_GT(num_chars, 0);
- pos += static_cast<size_t>(num_chars);
- }
- return true;
- }
- bool SupportsCoreIdleTimes() {
- // Reading from the cpuidle driver doesn't block.
- ThreadRestrictions::ScopedAllowIO allow_io;
- // Check if the path for the idle time in state 0 for core 0 is readable.
- FilePath idle_state0_path(StringPrintf(
- kCoreIdleStateTimePath, /*core_index=*/size_t{0}, /*idle_state=*/0));
- ScopedFILE file_stream(OpenFile(idle_state0_path, "rb"));
- return static_cast<bool>(file_stream);
- }
- std::vector<CPU::CoreType> GuessCoreTypes() {
- // Try to guess the CPU architecture and cores of each cluster by comparing
- // the maximum frequencies of the available (online and offline) cores.
- const char kCPUMaxFreqPath[] =
- "/sys/devices/system/cpu/cpu%" PRIuS "/cpufreq/cpuinfo_max_freq";
- size_t num_cpus = static_cast<size_t>(SysInfo::NumberOfProcessors());
- std::vector<CPU::CoreType> core_index_to_type(num_cpus,
- CPU::CoreType::kUnknown);
- std::vector<uint32_t> max_core_frequencies_mhz(num_cpus, 0);
- flat_set<uint32_t> frequencies_mhz;
- {
- // Reading from cpuinfo_max_freq doesn't block (it amounts to reading a
- // struct field from the cpufreq kernel driver).
- ThreadRestrictions::ScopedAllowIO allow_io;
- for (size_t core_index = 0; core_index < num_cpus; ++core_index) {
- std::string content;
- uint32_t frequency_khz = 0;
- auto path = StringPrintf(kCPUMaxFreqPath, core_index);
- if (ReadFileToString(FilePath(path), &content))
- StringToUint(content, &frequency_khz);
- uint32_t frequency_mhz = frequency_khz / 1000;
- max_core_frequencies_mhz[core_index] = frequency_mhz;
- if (frequency_mhz > 0)
- frequencies_mhz.insert(frequency_mhz);
- }
- }
- size_t num_frequencies = frequencies_mhz.size();
- for (size_t core_index = 0; core_index < num_cpus; ++core_index) {
- uint32_t core_frequency_mhz = max_core_frequencies_mhz[core_index];
- CPU::CoreType core_type = CPU::CoreType::kOther;
- if (num_frequencies == 1u) {
- core_type = CPU::CoreType::kSymmetric;
- } else if (num_frequencies == 2u || num_frequencies == 3u) {
- auto it = frequencies_mhz.find(core_frequency_mhz);
- if (it != frequencies_mhz.end()) {
- // flat_set is sorted.
- ptrdiff_t frequency_index = it - frequencies_mhz.begin();
- switch (frequency_index) {
- case 0:
- core_type = num_frequencies == 2u
- ? CPU::CoreType::kBigLittle_Little
- : CPU::CoreType::kBigLittleBigger_Little;
- break;
- case 1:
- core_type = num_frequencies == 2u
- ? CPU::CoreType::kBigLittle_Big
- : CPU::CoreType::kBigLittleBigger_Big;
- break;
- case 2:
- DCHECK_EQ(num_frequencies, 3u);
- core_type = CPU::CoreType::kBigLittleBigger_Bigger;
- break;
- default:
- NOTREACHED();
- break;
- }
- }
- }
- core_index_to_type[core_index] = core_type;
- }
- return core_index_to_type;
- }
- } // namespace
- // static
- const std::vector<CPU::CoreType>& CPU::GetGuessedCoreTypes() {
- static NoDestructor<std::vector<CoreType>> kCoreTypes(GuessCoreTypes());
- return *kCoreTypes.get();
- }
- // static
- bool CPU::GetTimeInState(TimeInState& time_in_state) {
- time_in_state.clear();
- // The kernel may not support the cpufreq-stats driver.
- static const bool kSupportsTimeInState = SupportsTimeInState();
- if (!kSupportsTimeInState)
- return false;
- static const std::vector<CoreType>& kCoreTypes = GetGuessedCoreTypes();
- // time_in_state is reported per cluster. Identify the first cores of each
- // cluster.
- static NoDestructor<std::vector<size_t>> kFirstCoresIndexes([]() {
- std::vector<size_t> first_cores;
- int last_core_package_id = 0;
- for (size_t core_index = 0;
- core_index < static_cast<size_t>(SysInfo::NumberOfProcessors());
- core_index++) {
- // Reading from physical_package_id doesn't block (it amounts to reading a
- // struct field from the kernel).
- ThreadRestrictions::ScopedAllowIO allow_io;
- FilePath package_id_path(
- StringPrintf(kPhysicalPackageIdPath, core_index));
- std::string package_id_str;
- if (!ReadFileToString(package_id_path, &package_id_str))
- return std::vector<size_t>();
- int package_id;
- base::StringPiece trimmed = base::TrimWhitespaceASCII(
- package_id_str, base::TrimPositions::TRIM_ALL);
- if (!base::StringToInt(trimmed, &package_id))
- return std::vector<size_t>();
- if (last_core_package_id != package_id || core_index == 0)
- first_cores.push_back(core_index);
- last_core_package_id = package_id;
- }
- return first_cores;
- }());
- if (kFirstCoresIndexes->empty())
- return false;
- // Reading from time_in_state doesn't block (it amounts to reading a struct
- // from the cpufreq-stats kernel driver).
- ThreadRestrictions::ScopedAllowIO allow_io;
- // Read the time_in_state for each cluster from the /sys directory of the
- // cluster's first core.
- for (size_t cluster_core_index : *kFirstCoresIndexes) {
- FilePath time_in_state_path(
- StringPrintf(kTimeInStatePath, cluster_core_index));
- std::string buffer;
- if (!ReadFileToString(time_in_state_path, &buffer))
- return false;
- if (!ParseTimeInState(buffer, kCoreTypes[cluster_core_index],
- cluster_core_index, time_in_state)) {
- return false;
- }
- }
- return true;
- }
- // static
- bool CPU::GetCumulativeCoreIdleTimes(CoreIdleTimes& idle_times) {
- idle_times.clear();
- // The kernel may not support the cpufreq-stats driver.
- static const bool kSupportsIdleTimes = SupportsCoreIdleTimes();
- if (!kSupportsIdleTimes)
- return false;
- // Reading from the cpuidle driver doesn't block.
- ThreadRestrictions::ScopedAllowIO allow_io;
- size_t num_cpus = static_cast<size_t>(SysInfo::NumberOfProcessors());
- bool success = false;
- for (size_t core_index = 0; core_index < num_cpus; ++core_index) {
- std::string content;
- TimeDelta idle_time;
- // The number of idle states is system/CPU dependent, so we increment and
- // try to read each state until we fail.
- for (int state_index = 0;; ++state_index) {
- auto path = StringPrintf(kCoreIdleStateTimePath, core_index, state_index);
- uint64_t idle_state_time = 0;
- if (!ReadFileToString(FilePath(path), &content))
- break;
- StringToUint64(content, &idle_state_time);
- idle_time += Microseconds(idle_state_time);
- }
- idle_times.push_back(idle_time);
- // At least one of the cores should have some idle time, otherwise we report
- // a failure.
- success |= idle_time.is_positive();
- }
- return success;
- }
- #endif // BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) ||
- // BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_AIX)
- const CPU& CPU::GetInstanceNoAllocation() {
- static const base::NoDestructor<const CPU> cpu(CPU(false));
- return *cpu;
- }
- } // namespace base
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