blob: 05a60f45373e781951dfc5e508d408feaced104a [file] [log] [blame]
// Copyright 2018 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/atomicops.h"
#include "base/base_export.h"
#include "base/files/scoped_file.h"
#include "base/memory/scoped_refptr.h"
#include "base/trace_event/trace_log.h"
namespace base {
class SingleThreadTaskRunner;
namespace trace_event {
// A delegate to isolate CPU frequency monitor functionality mainly for testing.
class BASE_EXPORT CPUFreqMonitorDelegate {
virtual ~CPUFreqMonitorDelegate() = default;
// Returns a vector of the minimal set of CPU IDs that we need to monitor to
// get CPU frequency information. For CPUs that operate cores in a cluster,
// i.e. modern Qualcomm 8 cores, this is CPU0 and CPU4.
virtual void GetCPUIds(std::vector<unsigned int>* ids) const;
// Reads the kernel_max_cpu file to determine the max CPU ID, i.e. 7 on an
// 8-core CPU.
virtual unsigned int GetKernelMaxCPUs() const;
// Reads the frequency from the CPUs being monitored and records them.
virtual void RecordFrequency(unsigned int cpu_id, unsigned int freq);
// Returns whether or not the tracing category our CPU Frequency counters are
// in is enabled to determine if we should record.
virtual bool IsTraceCategoryEnabled() const;
// Gets the path to CPU frequency related files for a particular CPU ID.
virtual std::string GetScalingCurFreqPathString(unsigned int cpu_id) const;
virtual std::string GetRelatedCPUsPathString(unsigned int cpu_id) const;
// Allows us to delay creating a task runner, necessary because many tests
// don't like us creating one outside of a ScopedTaskEnvironment.
virtual scoped_refptr<SingleThreadTaskRunner> CreateTaskRunner();
// A class for monitoring the CPU frequency on unique cores/clusters.
class BASE_EXPORT CPUFreqMonitor : public TraceLog::EnabledStateObserver {
// Overhead of reading one cluster on a Nexus 6P is ~0.1ms per CPU. 50ms seems
// frequent enough to get a general idea of CPU frequency trends.
static const size_t kDefaultCPUFreqSampleIntervalMs = 50;
~CPUFreqMonitor() override;
static CPUFreqMonitor* GetInstance();
void Start();
void Stop();
// TraceLog::EnabledStateObserver.
void OnTraceLogEnabled() override;
void OnTraceLogDisabled() override;
bool IsEnabledForTesting();
friend class CPUFreqMonitorTest;
CPUFreqMonitor(std::unique_ptr<CPUFreqMonitorDelegate> delegate);
void Sample(std::vector<std::pair<unsigned int, base::ScopedFD>> fds);
// Uses the delegate's CreateTaskRunner function to lazily create a task
// runner so we don't illegally create a task runner on Chrome startup for
// various tests.
const scoped_refptr<SingleThreadTaskRunner>& GetOrCreateTaskRunner();
base::subtle::Atomic32 is_enabled_ = 0;
scoped_refptr<SingleThreadTaskRunner> task_runner_;
std::unique_ptr<CPUFreqMonitorDelegate> delegate_;
base::WeakPtrFactory<CPUFreqMonitor> weak_ptr_factory_;
} // namespace trace_event
} // namespace base