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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
// The Gecko Profiler is an always-on profiler that takes fast and low overhead
// samples of the program execution using only userspace functionality for
// portability. The goal of this module is to provide performance data in a
// generic cross-platform way without requiring custom tools or kernel support.
// Samples are collected to form a timeline with optional timeline event
// (markers) used for filtering. The samples include both native stacks and
// platform-independent "label stack" frames.
#ifndef BaseProfiler_h
#define BaseProfiler_h
// This file is safe to include unconditionally, and only defines
// empty macros if MOZ_GECKO_PROFILER is not set.
// These headers are also safe to include unconditionally, with empty macros if
// MOZ_GECKO_PROFILER is not set.
// If your file only uses particular APIs (e.g., only markers), please consider
// including only the needed headers instead of this one, to reduce compilation
// dependencies.
#include "mozilla/BaseProfilerCounts.h"
#include "mozilla/BaseProfilerLabels.h"
#include "mozilla/BaseProfilerMarkers.h"
#include "mozilla/BaseProfilerState.h"
# include "mozilla/UniquePtr.h"
// This file can be #included unconditionally. However, everything within this
// file must be guarded by a #ifdef MOZ_GECKO_PROFILER, *except* for the
// following macros and functions, which encapsulate the most common operations
// and thus avoid the need for many #ifdefs.
// Function stubs for when MOZ_GECKO_PROFILER is not defined.
namespace mozilla {
namespace baseprofiler {
// This won't be used, it's just there to allow the empty definition of
// `profiler_get_backtrace`.
struct ProfilerBacktrace {};
using UniqueProfilerBacktrace = UniquePtr<ProfilerBacktrace>;
// Get/Capture-backtrace functions can return nullptr or false, the result
// should be fed to another empty macro or stub anyway.
static inline UniqueProfilerBacktrace profiler_get_backtrace() {
return nullptr;
static inline bool profiler_capture_backtrace_into(
ProfileChunkedBuffer& aChunkedBuffer, StackCaptureOptions aCaptureOptions) {
return false;
static inline UniquePtr<ProfileChunkedBuffer> profiler_capture_backtrace() {
return nullptr;
static inline void profiler_init(void* stackTop) {}
static inline void profiler_shutdown() {}
} // namespace baseprofiler
} // namespace mozilla
# include "BaseProfilingStack.h"
# include "mozilla/Assertions.h"
# include "mozilla/Atomics.h"
# include "mozilla/Attributes.h"
# include "mozilla/Maybe.h"
# include "mozilla/PowerOfTwo.h"
# include "mozilla/TimeStamp.h"
# include "mozilla/UniquePtr.h"
# include <functional>
# include <stdint.h>
# include <string>
namespace mozilla {
class MallocAllocPolicy;
class ProfileChunkedBuffer;
enum class StackCaptureOptions;
template <class T, size_t MinInlineCapacity, class AllocPolicy>
class Vector;
namespace baseprofiler {
class ProfilerBacktrace;
class SpliceableJSONWriter;
// Start and stop the profiler
static constexpr PowerOfTwo32 BASE_PROFILER_DEFAULT_ENTRIES =
# if !defined(GP_PLAT_arm_android)
MakePowerOfTwo32<1024 * 1024>(); // 1M entries = 8MB
# else
MakePowerOfTwo32<128 * 1024>(); // 128k entries = 1MB
# endif
// Startup profiling usually need to capture more data, especially on slow
// systems.
# if !defined(GP_PLAT_arm_android)
MakePowerOfTwo32<4 * 1024 * 1024>(); // 4M entries = 32MB
# else
MakePowerOfTwo32<256 * 1024>(); // 256k entries = 2MB
# endif
// Initialize the profiler. If MOZ_PROFILER_STARTUP is set the profiler will
// also be started. This call must happen before any other profiler calls
// (except profiler_start(), which will call profiler_init() if it hasn't
// already run).
MFBT_API void profiler_init(void* stackTop);
::mozilla::baseprofiler::AutoProfilerInit BASE_PROFILER_RAII
// Clean up the profiler module, stopping it if required. This function may
// also save a shutdown profile if requested. No profiler calls should happen
// after this point and all profiling stack labels should have been popped.
MFBT_API void profiler_shutdown();
// Start the profiler -- initializing it first if necessary -- with the
// selected options. Stops and restarts the profiler if it is already active.
// After starting the profiler is "active". The samples will be recorded in a
// circular buffer.
// "aCapacity" is the maximum number of 8-byte entries in the profiler's
// circular buffer.
// "aInterval" the sampling interval, measured in millseconds.
// "aFeatures" is the feature set. Features unsupported by this
// platform/configuration are ignored.
// "aFilters" is the list of thread filters. Threads that do not match any
// of the filters are not profiled. A filter matches a thread if
// (a) the thread name contains the filter as a case-insensitive
// substring, or
// (b) the filter is of the form "pid:<n>" where n is the process
// id of the process that the thread is running in.
// "aDuration" is the duration of entries in the profiler's circular buffer.
MFBT_API void profiler_start(PowerOfTwo32 aCapacity, double aInterval,
uint32_t aFeatures, const char** aFilters,
uint32_t aFilterCount,
const Maybe<double>& aDuration = Nothing());
// Stop the profiler and discard the profile without saving it. A no-op if the
// profiler is inactive. After stopping the profiler is "inactive".
MFBT_API void profiler_stop();
// If the profiler is inactive, start it. If it's already active, restart it if
// the requested settings differ from the current settings. Both the check and
// the state change are performed while the profiler state is locked.
// The only difference to profiler_start is that the current buffer contents are
// not discarded if the profiler is already running with the requested settings.
MFBT_API void profiler_ensure_started(
PowerOfTwo32 aCapacity, double aInterval, uint32_t aFeatures,
const char** aFilters, uint32_t aFilterCount,
const Maybe<double>& aDuration = Nothing());
// Control the profiler
// Register/unregister threads with the profiler. Both functions operate the
// same whether the profiler is active or inactive.
do { \
char stackTop; \
::mozilla::baseprofiler::profiler_register_thread(name, &stackTop); \
} while (0)
MFBT_API ProfilingStack* profiler_register_thread(const char* name,
void* guessStackTop);
MFBT_API void profiler_unregister_thread();
// Registers a DOM Window (the JS global `window`) with the profiler. Each
// Window _roughly_ corresponds to a single document loaded within a
// browsing context. Both the Window Id and Browser Id are recorded to allow
// correlating different Windows loaded within the same tab or frame element.
// We register pages for each navigations but we do not register
// history.pushState or history.replaceState since they correspond to the same
// Inner Window ID. When a browsing context is first loaded, the first url
// loaded in it will be about:blank. Because of that, this call keeps the first
// non-about:blank registration of window and discards the previous one.
// "aTabID" is the BrowserId of that document belongs to.
// That's used to determine the tab of that page.
// "aInnerWindowID" is the ID of the `window` global object of that
// document.
// "aUrl" is the URL of the page.
// "aEmbedderInnerWindowID" is the inner window id of embedder. It's used to
// determine sub documents of a page.
MFBT_API void profiler_register_page(uint64_t aTabD, uint64_t aInnerWindowID,
const std::string& aUrl,
uint64_t aEmbedderInnerWindowID);
// Unregister page with the profiler.
// Take a Inner Window ID and unregister the page entry that has the same ID.
MFBT_API void profiler_unregister_page(uint64_t aRegisteredInnerWindowID);
// Remove all registered and unregistered pages in the profiler.
void profiler_clear_all_pages();
class BaseProfilerCount;
MFBT_API void profiler_add_sampled_counter(BaseProfilerCount* aCounter);
MFBT_API void profiler_remove_sampled_counter(BaseProfilerCount* aCounter);
// Register and unregister a thread within a scope.
::mozilla::baseprofiler::AutoProfilerRegisterThread BASE_PROFILER_RAII(name)
// Pause and resume the profiler. No-ops if the profiler is inactive. While
// paused the profile will not take any samples and will not record any data
// into its buffers. The profiler remains fully initialized in this state.
// This feature will keep JavaScript profiling enabled, thus allowing toggling
// the profiler without invalidating the JIT.
MFBT_API void profiler_pause();
MFBT_API void profiler_resume();
// Only pause and resume the periodic sampling loop, including stack sampling,
// counters, and profiling overheads.
MFBT_API void profiler_pause_sampling();
MFBT_API void profiler_resume_sampling();
// These functions tell the profiler that a thread went to sleep so that we can
// avoid sampling it while it's sleeping. Calling profiler_thread_sleep()
// twice without an intervening profiler_thread_wake() is an error. All three
// functions operate the same whether the profiler is active or inactive.
MFBT_API void profiler_thread_sleep();
MFBT_API void profiler_thread_wake();
// Mark a thread as asleep/awake within a scope.
::mozilla::baseprofiler::AutoProfilerThreadSleep BASE_PROFILER_RAII
::mozilla::baseprofiler::AutoProfilerThreadWake BASE_PROFILER_RAII
// Get information from the profiler
// Get the params used to start the profiler. Returns 0 and an empty vector
// (via outparams) if the profile is inactive. It's possible that the features
// returned may be slightly different to those requested due to required
// adjustments.
MFBT_API void profiler_get_start_params(
int* aEntrySize, Maybe<double>* aDuration, double* aInterval,
uint32_t* aFeatures, Vector<const char*, 0, MallocAllocPolicy>* aFilters);
// The number of milliseconds since the process started. Operates the same
// whether the profiler is active or inactive.
MFBT_API double profiler_time();
// An object of this class is passed to profiler_suspend_and_sample_thread().
// For each stack frame, one of the Collect methods will be called.
class ProfilerStackCollector {
// Some collectors need to worry about possibly overwriting previous
// generations of data. If that's not an issue, this can return Nothing,
// which is the default behaviour.
virtual Maybe<uint64_t> SamplePositionInBuffer() { return Nothing(); }
virtual Maybe<uint64_t> BufferRangeStart() { return Nothing(); }
// This method will be called once if the thread being suspended is the main
// thread. Default behaviour is to do nothing.
virtual void SetIsMainThread() {}
// WARNING: The target thread is suspended when the Collect methods are
// called. Do not try to allocate or acquire any locks, or you could
// deadlock. The target thread will have resumed by the time this function
// returns.
virtual void CollectNativeLeafAddr(void* aAddr) = 0;
virtual void CollectProfilingStackFrame(
const ProfilingStackFrame& aFrame) = 0;
// This method suspends the thread identified by aThreadId, samples its
// profiling stack, JS stack, and (optionally) native stack, passing the
// collected frames into aCollector. aFeatures dictates which compiler features
// are used. |Leaf| is the only relevant one.
// Use `aThreadId`=0 to sample the current thread.
MFBT_API void profiler_suspend_and_sample_thread(
int aThreadId, uint32_t aFeatures, ProfilerStackCollector& aCollector,
bool aSampleNative = true);
struct ProfilerBacktraceDestructor {
MFBT_API void operator()(ProfilerBacktrace*);
using UniqueProfilerBacktrace =
UniquePtr<ProfilerBacktrace, ProfilerBacktraceDestructor>;
// Immediately capture the current thread's call stack, store it in the provided
// buffer (usually to avoid allocations if you can construct the buffer on the
// stack). Returns false if unsuccessful, if the profiler is inactive, or if
// aCaptureOptions is NoStack.
MFBT_API bool profiler_capture_backtrace_into(
ProfileChunkedBuffer& aChunkedBuffer, StackCaptureOptions aCaptureOptions);
// Immediately capture the current thread's call stack, and return it in a
// ProfileChunkedBuffer (usually for later use in MarkerStack::TakeBacktrace()).
// May be null if unsuccessful, or if the profiler is inactive.
MFBT_API UniquePtr<ProfileChunkedBuffer> profiler_capture_backtrace();
// Immediately capture the current thread's call stack, and return it in a
// ProfilerBacktrace (usually for later use in marker function that take a
// ProfilerBacktrace). May be null if unsuccessful, or if the profiler is
// inactive.
MFBT_API UniqueProfilerBacktrace profiler_get_backtrace();
struct ProfilerStats {
unsigned n = 0;
double sum = 0;
double min = std::numeric_limits<double>::max();
double max = 0;
void Count(double v) {
sum += v;
if (v < min) {
min = v;
if (v > max) {
max = v;
struct ProfilerBufferInfo {
// Index of the oldest entry.
uint64_t mRangeStart;
// Index of the newest entry.
uint64_t mRangeEnd;
// Buffer capacity in number of 8-byte entries.
uint32_t mEntryCount;
// Sampling stats: Interval (us) between successive samplings.
ProfilerStats mIntervalsUs;
// Sampling stats: Total duration (us) of each sampling. (Split detail below.)
ProfilerStats mOverheadsUs;
// Sampling stats: Time (us) to acquire the lock before sampling.
ProfilerStats mLockingsUs;
// Sampling stats: Time (us) to discard expired data.
ProfilerStats mCleaningsUs;
// Sampling stats: Time (us) to collect counter data.
ProfilerStats mCountersUs;
// Sampling stats: Time (us) to sample thread stacks.
ProfilerStats mThreadsUs;
// Get information about the current buffer status.
// Returns Nothing() if the profiler is inactive.
// This information may be useful to a user-interface displaying the current
// status of the profiler, allowing the user to get a sense for how fast the
// buffer is being written to, and how much data is visible.
MFBT_API Maybe<ProfilerBufferInfo> profiler_get_buffer_info();
} // namespace baseprofiler
} // namespace mozilla
namespace mozilla {
namespace baseprofiler {
// Put profiling data into the profiler (markers)
MFBT_API void profiler_add_js_marker(const char* aMarkerName,
const char* aMarkerText);
// Output profiles
// Set a user-friendly process name, used in JSON stream.
MFBT_API void profiler_set_process_name(const std::string& aProcessName,
const std::string* aETLDplus1);
// Get the profile encoded as a JSON string. A no-op (returning nullptr) if the
// profiler is inactive.
// If aIsShuttingDown is true, the current time is included as the process
// shutdown time in the JSON's "meta" object.
MFBT_API UniquePtr<char[]> profiler_get_profile(double aSinceTime = 0,
bool aIsShuttingDown = false,
bool aOnlyThreads = false);
// Write the profile for this process (excluding subprocesses) into aWriter.
// Returns false if the profiler is inactive.
MFBT_API bool profiler_stream_json_for_this_process(
SpliceableJSONWriter& aWriter, double aSinceTime = 0,
bool aIsShuttingDown = false, bool aOnlyThreads = false);
// Get the profile and write it into a file. A no-op if the profile is
// inactive.
MFBT_API void profiler_save_profile_to_file(const char* aFilename);
// RAII classes
class MOZ_RAII AutoProfilerInit {
explicit AutoProfilerInit() { profiler_init(this); }
~AutoProfilerInit() { profiler_shutdown(); }
// Convenience class to register and unregister a thread with the profiler.
// Needs to be the first object on the stack of the thread.
class MOZ_RAII AutoProfilerRegisterThread final {
explicit AutoProfilerRegisterThread(const char* aName) {
profiler_register_thread(aName, this);
~AutoProfilerRegisterThread() { profiler_unregister_thread(); }
AutoProfilerRegisterThread(const AutoProfilerRegisterThread&) = delete;
AutoProfilerRegisterThread& operator=(const AutoProfilerRegisterThread&) =
class MOZ_RAII AutoProfilerThreadSleep {
explicit AutoProfilerThreadSleep() { profiler_thread_sleep(); }
~AutoProfilerThreadSleep() { profiler_thread_wake(); }
// Temporarily wake up the profiling of a thread while servicing events such as
// Asynchronous Procedure Calls (APCs).
class MOZ_RAII AutoProfilerThreadWake {
explicit AutoProfilerThreadWake()
: mIssuedWake(profiler_thread_is_sleeping()) {
if (mIssuedWake) {
~AutoProfilerThreadWake() {
if (mIssuedWake) {
bool mIssuedWake;
// Get the MOZ_PROFILER_STARTUP* environment variables that should be
// supplied to a child process that is about to be launched, in order
// to make that child process start with the same profiler settings as
// in the current process. The given function is invoked once for
// each variable to be set.
MFBT_API void GetProfilerEnvVarsForChildProcess(
std::function<void(const char* key, const char* value)>&& aSetEnv);
} // namespace baseprofiler
} // namespace mozilla
#endif // BaseProfiler_h