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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 "content/common/android/cpu_affinity.h"
#include "content/public/common/cpu_affinity.h"
#include "base/command_line.h"
#include "base/cpu.h"
#include "base/cpu_affinity_posix.h"
#include "base/metrics/histogram_functions.h"
#include "base/no_destructor.h"
#include "base/process/internal_linux.h"
#include "base/process/process_handle.h"
#include "base/task/current_thread.h"
#include "base/task/task_observer.h"
#include "base/threading/thread_task_runner_handle.h"
namespace {
void ApplyProcessCpuAffinityMode(base::CpuAffinityMode mode) {
// Restrict affinity of all existing threads of the current process. The
// affinity is inherited by any subsequently created thread. Other threads may
// already exist even during early startup (e.g. Java threads like
// RenderThread), so setting the affinity only for the current thread is not
// enough here.
bool success =
base::SetProcessCpuAffinityMode(base::GetCurrentProcessHandle(), mode);
base::UmaHistogramBoolean(
"Power.CpuAffinityExperiments.ProcessAffinityUpdateSuccess", success);
}
class CpuAffinityTaskObserver : public base::TaskObserver {
public:
CpuAffinityTaskObserver() {}
static CpuAffinityTaskObserver* GetInstance() {
static base::NoDestructor<CpuAffinityTaskObserver> instance;
return instance.get();
}
void WillProcessTask(const base::PendingTask& pending_task,
bool was_blocked_or_low_priority) override {}
void DidProcessTask(const base::PendingTask& pending_task) override {
++task_counter_;
if (task_counter_ == kUpdateAfterEveryNTasks) {
if (enforced_mode_ &&
*enforced_mode_ != base::CurrentThreadCpuAffinityMode()) {
ApplyProcessCpuAffinityMode(*enforced_mode_);
}
task_counter_ = 0;
}
}
void InitializeCpuAffinity(base::CpuAffinityMode mode) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// For now, affinity modes only have an effect on big.LITTLE architectures.
if (!base::HasBigCpuCores())
return;
enforced_mode_ = mode;
ApplyProcessCpuAffinityMode(mode);
// Set up task observer if it's already possible. Otherwise it will be set
// up after thread initialization (see app/content_main_runner_impl.cc and
// child/child_process.cc).
if (base::CurrentThread::IsSet())
SetupCpuAffinityPolling();
}
void SetupCpuAffinityPollingOnce() {
// The polling should be set up once from the main thread. Subsequent calls
// from other threads should be ignored.
if (did_call_setup_)
return;
SetupCpuAffinityPolling();
did_call_setup_ = true;
}
private:
void SetupCpuAffinityPolling() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (!base::HasBigCpuCores() || !enforced_mode_ || did_setup_polling_)
return;
base::CurrentThread::Get()->AddTaskObserver(this);
did_setup_polling_ = true;
}
SEQUENCE_CHECKER(sequence_checker_);
static constexpr int kUpdateAfterEveryNTasks = 100;
int task_counter_ = 0;
bool did_setup_polling_ = false;
bool did_call_setup_ = false;
base::Optional<base::CpuAffinityMode> enforced_mode_;
};
} // anonymous namespace
namespace content {
void EnforceProcessCpuAffinity(base::CpuAffinityMode mode) {
CpuAffinityTaskObserver::GetInstance()->InitializeCpuAffinity(mode);
}
void SetupCpuAffinityPollingOnce() {
CpuAffinityTaskObserver::GetInstance()->SetupCpuAffinityPollingOnce();
}
} // namespace content
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