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// Copyright 2020 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_affinity_posix.h"
#include <sched.h>
#include "base/cpu.h"
#include "base/process/internal_linux.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
namespace base {
namespace {
const cpu_set_t& AllCores() {
static const cpu_set_t kAllCores = []() {
cpu_set_t set;
CPU_ZERO(&set);
const std::vector<CPU::CoreType>& core_types = CPU::GetGuessedCoreTypes();
if (core_types.empty()) {
memset(&set, 0xff, sizeof(set));
} else {
for (size_t index = 0; index < core_types.size(); index++)
CPU_SET(index, &set);
}
return set;
}();
return kAllCores;
}
const cpu_set_t& LittleCores() {
static const cpu_set_t kLittleCores = []() {
const std::vector<CPU::CoreType>& core_types = CPU::GetGuessedCoreTypes();
if (core_types.empty())
return AllCores();
cpu_set_t set;
CPU_ZERO(&set);
for (size_t core_index = 0; core_index < core_types.size(); core_index++) {
switch (core_types[core_index]) {
case CPU::CoreType::kUnknown:
case CPU::CoreType::kOther:
case CPU::CoreType::kSymmetric:
// In the presence of an unknown core type or symmetric architecture,
// fall back to allowing all cores.
return AllCores();
case CPU::CoreType::kBigLittle_Little:
case CPU::CoreType::kBigLittleBigger_Little:
CPU_SET(core_index, &set);
break;
case CPU::CoreType::kBigLittle_Big:
case CPU::CoreType::kBigLittleBigger_Big:
case CPU::CoreType::kBigLittleBigger_Bigger:
break;
}
}
return set;
}();
return kLittleCores;
}
} // anonymous namespace
bool HasBigCpuCores() {
static const bool kHasBigCores = []() {
const std::vector<CPU::CoreType>& core_types = CPU::GetGuessedCoreTypes();
if (core_types.empty())
return false;
for (CPU::CoreType core_type : core_types) {
switch (core_type) {
case CPU::CoreType::kUnknown:
case CPU::CoreType::kOther:
case CPU::CoreType::kSymmetric:
return false;
case CPU::CoreType::kBigLittle_Little:
case CPU::CoreType::kBigLittleBigger_Little:
case CPU::CoreType::kBigLittle_Big:
case CPU::CoreType::kBigLittleBigger_Big:
case CPU::CoreType::kBigLittleBigger_Bigger:
return true;
}
}
return false;
}();
return kHasBigCores;
}
bool SetThreadCpuAffinityMode(PlatformThreadId thread_id,
CpuAffinityMode affinity) {
int result = 0;
switch (affinity) {
case CpuAffinityMode::kDefault: {
const cpu_set_t& all_cores = AllCores();
result = sched_setaffinity(thread_id, sizeof(all_cores), &all_cores);
break;
}
case CpuAffinityMode::kLittleCoresOnly: {
const cpu_set_t& little_cores = LittleCores();
result =
sched_setaffinity(thread_id, sizeof(little_cores), &little_cores);
break;
}
}
return result == 0;
}
bool SetProcessCpuAffinityMode(ProcessHandle process_handle,
CpuAffinityMode affinity) {
bool any_threads = false;
bool result = true;
internal::ForEachProcessTask(
process_handle, [&any_threads, &result, affinity](
PlatformThreadId tid, const FilePath& /*task_path*/) {
any_threads = true;
result &= SetThreadCpuAffinityMode(tid, affinity);
});
return any_threads && result;
}
absl::optional<CpuAffinityMode> CurrentThreadCpuAffinityMode() {
if (HasBigCpuCores()) {
cpu_set_t set;
sched_getaffinity(PlatformThread::CurrentId(), sizeof(set), &set);
if (CPU_EQUAL(&set, &AllCores()))
return CpuAffinityMode::kDefault;
if (CPU_EQUAL(&set, &LittleCores()))
return CpuAffinityMode::kLittleCoresOnly;
}
return absl::nullopt;
}
} // namespace base
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