diff options
Diffstat (limited to 'third_party/abseil_cpp/absl/base/internal/sysinfo.cc')
| -rw-r--r-- | third_party/abseil_cpp/absl/base/internal/sysinfo.cc | 425 |
1 files changed, 0 insertions, 425 deletions
diff --git a/third_party/abseil_cpp/absl/base/internal/sysinfo.cc b/third_party/abseil_cpp/absl/base/internal/sysinfo.cc deleted file mode 100644 index 6c69683faf..0000000000 --- a/third_party/abseil_cpp/absl/base/internal/sysinfo.cc +++ /dev/null @@ -1,425 +0,0 @@ -// Copyright 2017 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -#include "absl/base/internal/sysinfo.h" - -#include "absl/base/attributes.h" - -#ifdef _WIN32 -#include <windows.h> -#else -#include <fcntl.h> -#include <pthread.h> -#include <sys/stat.h> -#include <sys/types.h> -#include <unistd.h> -#endif - -#ifdef __linux__ -#include <sys/syscall.h> -#endif - -#if defined(__APPLE__) || defined(__FreeBSD__) -#include <sys/sysctl.h> -#endif - -#if defined(__myriad2__) -#include <rtems.h> -#endif - -#include <string.h> -#include <cassert> -#include <cstdint> -#include <cstdio> -#include <cstdlib> -#include <ctime> -#include <limits> -#include <thread> // NOLINT(build/c++11) -#include <utility> -#include <vector> - -#include "absl/base/call_once.h" -#include "absl/base/internal/raw_logging.h" -#include "absl/base/internal/spinlock.h" -#include "absl/base/internal/unscaledcycleclock.h" -#include "absl/base/thread_annotations.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace base_internal { - -static int GetNumCPUs() { -#if defined(__myriad2__) - return 1; -#else - // Other possibilities: - // - Read /sys/devices/system/cpu/online and use cpumask_parse() - // - sysconf(_SC_NPROCESSORS_ONLN) - return std::thread::hardware_concurrency(); -#endif -} - -#if defined(_WIN32) - -static double GetNominalCPUFrequency() { -#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP) && \ - !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) - // UWP apps don't have access to the registry and currently don't provide an - // API informing about CPU nominal frequency. - return 1.0; -#else -#pragma comment(lib, "advapi32.lib") // For Reg* functions. - HKEY key; - // Use the Reg* functions rather than the SH functions because shlwapi.dll - // pulls in gdi32.dll which makes process destruction much more costly. - if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, - "HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0", 0, - KEY_READ, &key) == ERROR_SUCCESS) { - DWORD type = 0; - DWORD data = 0; - DWORD data_size = sizeof(data); - auto result = RegQueryValueExA(key, "~MHz", 0, &type, - reinterpret_cast<LPBYTE>(&data), &data_size); - RegCloseKey(key); - if (result == ERROR_SUCCESS && type == REG_DWORD && - data_size == sizeof(data)) { - return data * 1e6; // Value is MHz. - } - } - return 1.0; -#endif // WINAPI_PARTITION_APP && !WINAPI_PARTITION_DESKTOP -} - -#elif defined(CTL_HW) && defined(HW_CPU_FREQ) - -static double GetNominalCPUFrequency() { - unsigned freq; - size_t size = sizeof(freq); - int mib[2] = {CTL_HW, HW_CPU_FREQ}; - if (sysctl(mib, 2, &freq, &size, nullptr, 0) == 0) { - return static_cast<double>(freq); - } - return 1.0; -} - -#else - -// Helper function for reading a long from a file. Returns true if successful -// and the memory location pointed to by value is set to the value read. -static bool ReadLongFromFile(const char *file, long *value) { - bool ret = false; - int fd = open(file, O_RDONLY); - if (fd != -1) { - char line[1024]; - char *err; - memset(line, '\0', sizeof(line)); - int len = read(fd, line, sizeof(line) - 1); - if (len <= 0) { - ret = false; - } else { - const long temp_value = strtol(line, &err, 10); - if (line[0] != '\0' && (*err == '\n' || *err == '\0')) { - *value = temp_value; - ret = true; - } - } - close(fd); - } - return ret; -} - -#if defined(ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY) - -// Reads a monotonic time source and returns a value in -// nanoseconds. The returned value uses an arbitrary epoch, not the -// Unix epoch. -static int64_t ReadMonotonicClockNanos() { - struct timespec t; -#ifdef CLOCK_MONOTONIC_RAW - int rc = clock_gettime(CLOCK_MONOTONIC_RAW, &t); -#else - int rc = clock_gettime(CLOCK_MONOTONIC, &t); -#endif - if (rc != 0) { - perror("clock_gettime() failed"); - abort(); - } - return int64_t{t.tv_sec} * 1000000000 + t.tv_nsec; -} - -class UnscaledCycleClockWrapperForInitializeFrequency { - public: - static int64_t Now() { return base_internal::UnscaledCycleClock::Now(); } -}; - -struct TimeTscPair { - int64_t time; // From ReadMonotonicClockNanos(). - int64_t tsc; // From UnscaledCycleClock::Now(). -}; - -// Returns a pair of values (monotonic kernel time, TSC ticks) that -// approximately correspond to each other. This is accomplished by -// doing several reads and picking the reading with the lowest -// latency. This approach is used to minimize the probability that -// our thread was preempted between clock reads. -static TimeTscPair GetTimeTscPair() { - int64_t best_latency = std::numeric_limits<int64_t>::max(); - TimeTscPair best; - for (int i = 0; i < 10; ++i) { - int64_t t0 = ReadMonotonicClockNanos(); - int64_t tsc = UnscaledCycleClockWrapperForInitializeFrequency::Now(); - int64_t t1 = ReadMonotonicClockNanos(); - int64_t latency = t1 - t0; - if (latency < best_latency) { - best_latency = latency; - best.time = t0; - best.tsc = tsc; - } - } - return best; -} - -// Measures and returns the TSC frequency by taking a pair of -// measurements approximately `sleep_nanoseconds` apart. -static double MeasureTscFrequencyWithSleep(int sleep_nanoseconds) { - auto t0 = GetTimeTscPair(); - struct timespec ts; - ts.tv_sec = 0; - ts.tv_nsec = sleep_nanoseconds; - while (nanosleep(&ts, &ts) != 0 && errno == EINTR) {} - auto t1 = GetTimeTscPair(); - double elapsed_ticks = t1.tsc - t0.tsc; - double elapsed_time = (t1.time - t0.time) * 1e-9; - return elapsed_ticks / elapsed_time; -} - -// Measures and returns the TSC frequency by calling -// MeasureTscFrequencyWithSleep(), doubling the sleep interval until the -// frequency measurement stabilizes. -static double MeasureTscFrequency() { - double last_measurement = -1.0; - int sleep_nanoseconds = 1000000; // 1 millisecond. - for (int i = 0; i < 8; ++i) { - double measurement = MeasureTscFrequencyWithSleep(sleep_nanoseconds); - if (measurement * 0.99 < last_measurement && - last_measurement < measurement * 1.01) { - // Use the current measurement if it is within 1% of the - // previous measurement. - return measurement; - } - last_measurement = measurement; - sleep_nanoseconds *= 2; - } - return last_measurement; -} - -#endif // ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY - -static double GetNominalCPUFrequency() { - long freq = 0; - - // Google's production kernel has a patch to export the TSC - // frequency through sysfs. If the kernel is exporting the TSC - // frequency use that. There are issues where cpuinfo_max_freq - // cannot be relied on because the BIOS may be exporting an invalid - // p-state (on x86) or p-states may be used to put the processor in - // a new mode (turbo mode). Essentially, those frequencies cannot - // always be relied upon. The same reasons apply to /proc/cpuinfo as - // well. - if (ReadLongFromFile("/sys/devices/system/cpu/cpu0/tsc_freq_khz", &freq)) { - return freq * 1e3; // Value is kHz. - } - -#if defined(ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY) - // On these platforms, the TSC frequency is the nominal CPU - // frequency. But without having the kernel export it directly - // though /sys/devices/system/cpu/cpu0/tsc_freq_khz, there is no - // other way to reliably get the TSC frequency, so we have to - // measure it ourselves. Some CPUs abuse cpuinfo_max_freq by - // exporting "fake" frequencies for implementing new features. For - // example, Intel's turbo mode is enabled by exposing a p-state - // value with a higher frequency than that of the real TSC - // rate. Because of this, we prefer to measure the TSC rate - // ourselves on i386 and x86-64. - return MeasureTscFrequency(); -#else - - // If CPU scaling is in effect, we want to use the *maximum* - // frequency, not whatever CPU speed some random processor happens - // to be using now. - if (ReadLongFromFile("/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq", - &freq)) { - return freq * 1e3; // Value is kHz. - } - - return 1.0; -#endif // !ABSL_INTERNAL_UNSCALED_CYCLECLOCK_FREQUENCY_IS_CPU_FREQUENCY -} - -#endif - -ABSL_CONST_INIT static once_flag init_num_cpus_once; -ABSL_CONST_INIT static int num_cpus = 0; - -// NumCPUs() may be called before main() and before malloc is properly -// initialized, therefore this must not allocate memory. -int NumCPUs() { - base_internal::LowLevelCallOnce( - &init_num_cpus_once, []() { num_cpus = GetNumCPUs(); }); - return num_cpus; -} - -// A default frequency of 0.0 might be dangerous if it is used in division. -ABSL_CONST_INIT static once_flag init_nominal_cpu_frequency_once; -ABSL_CONST_INIT static double nominal_cpu_frequency = 1.0; - -// NominalCPUFrequency() may be called before main() and before malloc is -// properly initialized, therefore this must not allocate memory. -double NominalCPUFrequency() { - base_internal::LowLevelCallOnce( - &init_nominal_cpu_frequency_once, - []() { nominal_cpu_frequency = GetNominalCPUFrequency(); }); - return nominal_cpu_frequency; -} - -#if defined(_WIN32) - -pid_t GetTID() { - return pid_t{GetCurrentThreadId()}; -} - -#elif defined(__linux__) - -#ifndef SYS_gettid -#define SYS_gettid __NR_gettid -#endif - -pid_t GetTID() { - return syscall(SYS_gettid); -} - -#elif defined(__akaros__) - -pid_t GetTID() { - // Akaros has a concept of "vcore context", which is the state the program - // is forced into when we need to make a user-level scheduling decision, or - // run a signal handler. This is analogous to the interrupt context that a - // CPU might enter if it encounters some kind of exception. - // - // There is no current thread context in vcore context, but we need to give - // a reasonable answer if asked for a thread ID (e.g., in a signal handler). - // Thread 0 always exists, so if we are in vcore context, we return that. - // - // Otherwise, we know (since we are using pthreads) that the uthread struct - // current_uthread is pointing to is the first element of a - // struct pthread_tcb, so we extract and return the thread ID from that. - // - // TODO(dcross): Akaros anticipates moving the thread ID to the uthread - // structure at some point. We should modify this code to remove the cast - // when that happens. - if (in_vcore_context()) - return 0; - return reinterpret_cast<struct pthread_tcb *>(current_uthread)->id; -} - -#elif defined(__myriad2__) - -pid_t GetTID() { - uint32_t tid; - rtems_task_ident(RTEMS_SELF, 0, &tid); - return tid; -} - -#else - -// Fallback implementation of GetTID using pthread_getspecific. -ABSL_CONST_INIT static once_flag tid_once; -ABSL_CONST_INIT static pthread_key_t tid_key; -ABSL_CONST_INIT static absl::base_internal::SpinLock tid_lock( - absl::kConstInit, base_internal::SCHEDULE_KERNEL_ONLY); - -// We set a bit per thread in this array to indicate that an ID is in -// use. ID 0 is unused because it is the default value returned by -// pthread_getspecific(). -ABSL_CONST_INIT static std::vector<uint32_t> *tid_array - ABSL_GUARDED_BY(tid_lock) = nullptr; -static constexpr int kBitsPerWord = 32; // tid_array is uint32_t. - -// Returns the TID to tid_array. -static void FreeTID(void *v) { - intptr_t tid = reinterpret_cast<intptr_t>(v); - int word = tid / kBitsPerWord; - uint32_t mask = ~(1u << (tid % kBitsPerWord)); - absl::base_internal::SpinLockHolder lock(&tid_lock); - assert(0 <= word && static_cast<size_t>(word) < tid_array->size()); - (*tid_array)[word] &= mask; -} - -static void InitGetTID() { - if (pthread_key_create(&tid_key, FreeTID) != 0) { - // The logging system calls GetTID() so it can't be used here. - perror("pthread_key_create failed"); - abort(); - } - - // Initialize tid_array. - absl::base_internal::SpinLockHolder lock(&tid_lock); - tid_array = new std::vector<uint32_t>(1); - (*tid_array)[0] = 1; // ID 0 is never-allocated. -} - -// Return a per-thread small integer ID from pthread's thread-specific data. -pid_t GetTID() { - absl::call_once(tid_once, InitGetTID); - - intptr_t tid = reinterpret_cast<intptr_t>(pthread_getspecific(tid_key)); - if (tid != 0) { - return tid; - } - - int bit; // tid_array[word] = 1u << bit; - size_t word; - { - // Search for the first unused ID. - absl::base_internal::SpinLockHolder lock(&tid_lock); - // First search for a word in the array that is not all ones. - word = 0; - while (word < tid_array->size() && ~(*tid_array)[word] == 0) { - ++word; - } - if (word == tid_array->size()) { - tid_array->push_back(0); // No space left, add kBitsPerWord more IDs. - } - // Search for a zero bit in the word. - bit = 0; - while (bit < kBitsPerWord && (((*tid_array)[word] >> bit) & 1) != 0) { - ++bit; - } - tid = (word * kBitsPerWord) + bit; - (*tid_array)[word] |= 1u << bit; // Mark the TID as allocated. - } - - if (pthread_setspecific(tid_key, reinterpret_cast<void *>(tid)) != 0) { - perror("pthread_setspecific failed"); - abort(); - } - - return static_cast<pid_t>(tid); -} - -#endif - -} // namespace base_internal -ABSL_NAMESPACE_END -} // namespace absl |