CHANGELOG - third_party/perfetto - Git at Google

 Unreleased:
   Tracing service and probes:
     *
   Trace Processor:
     *
   UI:
     * Fixed ADB connection issues ("unable to reset device") on Windows and Mac.
   SDK:
     * Added support for writing track events using custom clock timestamps.


 v16.0 - 2021-06-01:
   Tracing service and probes:
     * Added support for building most targets (including traced, SDK and
       trace_processor_shell) from Windows using either clang-cl or MSVC 2019.
     * Added tracebox, a monolithic binary to capture traces with one command
       on Linux and older versions of Android (tested on Android Oreo).
     * Added support for service-side field-level filtering of traces. The
       consumer can pass a filter bytecode and ensure that non-allowed fields
       are never emitted in output.
     * Added reporting of service version and producer SDK version into the trace
       and `perfetto --query`.
     * Fixed compatibility with Android versions older than Pie (for sideloading)
       which cause failures when trying to enable atrace categories.
   Trace Processor:
     * Added new RPC interface based on a bidirectional binary pipe. This allows
       to simplify integration with out-of-process users. The existing --httpd
       interface now exposes a single /rpc endpoint. Older endpoints are still
       available for legacy clients.
     * Added support for counters and instant events in JSON traces.
     * Fixed support of displayTimeUnit in JSON traces.
   UI:
     * Added warning dialog when trying to use a trace_processor_shell --httpd
       which is too old.
     * Added warning dialog when trying to use a trace_processor_shell --httpd
       RPC instance from more than one tab.
     * Added links to convert the trace to JSON or systrace directly from the UI.
     * Changed track sorting logic. Tracks are now sorted in groups (e.g.,
       scheduling tracks, summary tracks, frame timeline tracks).
     * Fixed crashes happening flakily when pushing traces via window.open().


 v15.0 - 2021-05-05:
   Tracing service and probes:
     * Added support for {host,target}=aarch64 standalone builds.
     * Added --background cmdline switch to traced and traced_probes services.
     * Changed trigger_perfetto to ignore unknown command line arguments to
       preserve forward compatibility.
     * Added -a / --app cmdline argument to tools/record_android_trace.
   Trace Processor:
     * Added sanitisation of keys in nested debug annotation dictionaries.
     * Changed Android startup metric: count CPU time of JIT thread pool, report
       timestamp of activities during startup.
     * Changed android_surfaceflinger metric, added missed frame counters.
     * Changed version of SQLite to 3.35.4.
     * Fixed importing of JSON traces with decimal (sub-us) timestamp.
     * Fixed prepending "debug." prefix to debug annotations with non-interned
       names.
   UI:
     * Added support to visualize the lifetime of individual dmabuf allocations
       as async slices (datasource: already existing ftrace dmabuf event).
     * Fixed visualization of unfinished slices to extend to the end of the
       viewport.
   SDK:
     * Added support for passing arbitrary number of debug annotations to
       TRACE_EVENT and combining them with lambdas.
     * Added support for writing typed TrackEvent arguments using TRACE_EVENT
       inline without lambdas.
     * Changed ConvertTimestampToTraceTimeNs to be a member of
       TraceTimestampTraits<T> struct instead of a standalone function.
     * Changed TracedValue to use nested DebugAnnotation proto instead of
       DebugAnnotation::NestedValue.


 v14.0 - 2021-04-01:
   Tracing service and probes:
     * Added support for polling power rails on Android from the newer
       IPowerStats AIDL interface (previously using only the HAL interface).
     * Fixed native heap profiler crash when ABI of heapprofd and profiled
       process mismatch.
     * Changed encoding format of Anroid managed heap profiler to reduce heap
       dump sizes by delta-encoding object IDs.
   Trace Processor:
     * Added activity create/resume, layout inflation and resource timings to
       the Android startup metric.
     * Added chrome metadata key/value pairs (e.g. chrome version) into the
       `metadata` table with 'cr-' prefixed keys.
     * Added dma-buf-based memory metrics reporting total/avg/min/max dmabuf
       allocation per-dmabuf-heap and per-process.
     * Removed |force_full_sort| flag from config. This has been replaced
       by setting the sorting mode to force a full sort.
   UI:
     * Added tools/symbolize-ui-crash script to resolve crash reports via
       TypeScript source maps.
     * Fixed newlines when copying Android event log lines into the clipboard.
     * Fixed crash when selecting "Did not finish" slices.
     * Fixed OOM dialog to give actionable instructions when opening large traces
       rather than suggesting to file a bug.
   SDK:
     * Added /meson.build for bundling /sdk/perfetto.{cc,h} in Meson builds.
     * Added support for counter trace points with the TRACE_COUNTER macro.


 v13.0 - 2021-03-01:
   Tracing service and probes:
     * Added ability to sample callstacks using kernel tracepoints as timebase.
     * Added abililty to record the perf timebase counter values into the trace,
       both combined callstack+counter or counter-only.
     * Added abillity to trigger traces based on VM pressure on Android. Requires
       a dedicated tracing instance in $tracefs/instances/mm_events.
   Trace Processor:
     * Added sorting mode to trace processor config to specify how trace
       processor should sort events. The |force_full_sort| flag has been
       deprecated (with replacement) and will be removed in the next version.
     * Added ingestion of frame timeline events into the
       {expected,actual}_frame_timeline_slice tables.
     * Added support for Mali's trace_marker_write ftrace event.
     * Added memory metric based on newer android_fastrpc kernel events.
   UI:
     * Added flow events support for instant events and async tracks.
     * Added support for Android frame timeline events. They allow inspecting
       end-to-end expected vs actual app-to-surfaceflinger frame times.
     * Added ability to switch between Canary and Stable channels in the UI.
     * Added ability to drag&drop to open trace files.
     * Changed UI serving infrastructure, old ui versions can be now retrieved by
       directly opening https://ui.perfetto.dev/v12.1.269/ .
     * Removed thread state track for threads that have no activity.
   SDK:
     * Use process start time hashed with the process id as a unique process
       identifier, allowing multiple independent users of the SDK in the same
       process to interleave their events on shared tracks.
     * Record process and thread names into the trace.
     * Add ring buffer tracing support, i.e., periodic clearing of incremental
       state.
   Misc:
     * Convert python scripts to python3.


 v12.1 - 2021-02-01:
   Misc:
     * Fixed CHANGELOG which was missed in the 12.0 branch cut, causing
       mis-labeling of the version code in the v12.x branch as v11.0..N


 v12.0 - 2021-02-01:
   Tracing service and probes:
     * Added more helpful error messages if the client library is used without
       having been initialized.
     * Added //tools/record_android_trace script to facilitate recording traces
       from Android devices, automating start + stop-via-ctrl+c + pull + open.
     * Added auto-attachment of traces to Android bugreports if dumpstate is
       invoked when a trace with bugreport_score > 0 is running.
   SDK:
     * Added ability to customize the timestamp of events via
       ConvertTimestampToTraceTimeNs().
     * Fixed support for category names that contain a space.
   Trace Processor:
     * Added ingestion and query support for Android end-to-end frame timing
       events through the {actual, expected}_frame_timeline_slice tables.
     * Added time-to-reportFullyDrawn (Android's API) to startup metrics.
     * Fixed excessive memory usage when decoding traces containing callstacks
       (https://github.com/google/perfetto/issues/83).
   UI:
     * Added ability to inspect the full trace config string from the
       'Info and stats' page.
     * Fixed 'TABLE/VIEW XXX already exists' in the Metrics page when running the
       same metric twice.
     * Fixed sorting of tracks using numeric sorting instead of lexicographic:
       Thread {1, 2, 10, 11, 20} rather than Thread {1, 10, 11, 2, 20}.
     * Fixed CSP-related bug that was preventing the UI to work on Firefox.
     * Changed max zoom resolution to allow to zoom to sub-us events.


 v11.0 - 2021-01-01:
   Tracing service and probes:
     * Added trace packet interceptor API for rerouting trace data into
       non-Perfetto systems.
     * Added support for printing track events to the console.
     * Added a way to observe track event tracing sessions starting and
       stopping.
   Trace Processor:
     * Added "ancestor_slice" and "experimental_ancestor_stack_profile_callsite"
       table functions to look up ancestors of CPU stack samples in profiler
       tables.
     * Added power metric reporting suspend/resume time periods.
   UI:
     * Fixed CPU time calculation in example queries.
     * Added tracks to debug Android SystemUI jank.


 v10.0 - 2020-12-01:
   Tracing service and probes:
     * Fixed crash of tracing service if a client is unresponsive on the IPC
       channel. Clients are disconnected if they don't respond to IPCs for 10s.
     * Added cmdline arguments for integration within ChromeOS system image
       (--{producer,consumer}-socket-{group,mode} for chmod-ing sockets).
     * Changed path lookup logic for traced socket. /run/perfetto/ is used if the
       directory exists, falling back on /tmp/ otherwise.
     * Added support for kernel frame symbolization to the traced_perf callstack
       sampler.
     * Added support for resolving ftrace event arguments that require
       symbolization against printk_format.
   Trace Processor:
     * Added .read command to inject a SQL query file, similar to the -q cmdline.
     * Added trace-based metrics to root cause jank in Android System UI.
     * Added symbolization support for ELF files on Windows for heap and
       callstack profilers.
     * Added support for symbolizing names of workqueue ftrace events.
     * Improved Android startup metric with activity restart time.
   UI:
     * Added support for navigating flows with Ctrl+[ / Ctr+].
     * Improved query result panel, moved to the bottom group allowing
       simultaneous query result and timeline views.
     * Fixed data corruption when recording traces via the WebUSB-based Record
       page in the UI.


 v9.0 - 2020-11-01:
   Tracing service and probes:
     * Added support for recording traces from a system service through the
       client API.
     * The client library now reconnects producers automatically if the
       connection to the tracing service is lost. Also fixed crashes in ongoing
       tracing sessions when a disconnect occurs.
     * Added support for dpu and g2d ftrace events.
     * Enabled commit batching and producer side patching of chunks.
     * Add support for symbolizing kernel symbols for ftrace events.
   Trace Processor:
     * Fixed type affinity of string columns.
   UI:
     * Added initial support for running metrics from the UI.
     * Added support for displaying all flows when a slice or area is selected.
     * Highlight nodes that match the 'focus' string in the flamegraph.
     * Added search within slice args.
     * Fixed details panel height and moved query panel into details panel.
     * Enabled re-sharing of postMessage traces by echoing back the original URL.
     * Improved record page error messages.


 v8.0 - 2020-10-01:
   Tracing service and probes:
     * Added API for querying registered data sources and their capabilities.
     * Added support for profiling heap allocations on Linux via LD_PRELOAD.
     * Fixed possible race when initializing the consumer library.
     * Fixed subtle bugs on systems with 16KB system pages.
   Trace Processor:
     * Added a table which lists available metrics.
     * Added Python bindings on PyPi in the 'perfetto' package.
     * Added support for running trace_processor_shell on Android.
     * Added per-process metrics for GPU memory usage.
     * Added support for exporting flow events to JSON.
     * Added dynamic tables for navigating between slices of flows.
   UI:
     * Changed time marking: horizontal selection doesn't gray out anymore,
       pressing 'm' marks the range.
     * Added initial support for displaying flow event arrows.
     * Improved ordering of all thread tracks under process grouping.
     * Fixed UI crashes due to metric errors
     * Fixed selection of thread state slices.


 v7.0 - 2020-09-01:
   Tracing service and probes:
     * Added auto-reconnection to the SDK. Tracing::Initialize() now retries in
       the background, instead of failing, if the tracing service is unrechable.
     * Added support for recording cpuhp (CPU hotplug) ftrace events.
     * Fixed heap profiling unwinding on multi-ABI systems.
     * Fixed reporting of live objects in the native heap profiler when using
       --dump-at-max.
     * Fixed crash when writing trace events with field nesting level > 10.
   Trace Processor:
     * Added Python bindings, see
       https://perfetto.dev/docs/analysis/trace-processor#python-api .
     * Added ingestion for Chrome instant events and Chrome flow events.
     * Added ingestion for Android GPU memory events and sched_blocked_reason.
     * Added WebView power metric.
     * Added support for WSL1 where Async I/O is not available.
     * Improved detection of Android suspend/resume events.
   UI:
     * Added GPU memory recording controls and ingestion code. Requires a recent
       Android 12+ kernel.
     * Added details panel for flow events, showed when the user selects a slice
       involved in a flow (arrows in the UI are still being worked on).
     * Added instant events rendering.
     * Added Google Analytics.
     * Fixed I/O thread-states in 4.14 kernels to deal with the removal of
       wake-kill using sched_blocked_reason.
     * Fixed "Perfetto UI started debugging this browser" showing when opening
       the UI and the Chrome extension is installed.
   Misc:
     * Update language to comply with Android's inclusive language guidance.


 v6.0 - 2020-08-01:
   Tracing service and probes:
     * Added ftrace thermal events.
     * Added support for custom allocators to the heap profiler. Allows
       developers to report memory allocations that are not done through malloc.
     * Added detailed timestamping of key tracing session events.
     * Added support for building tracing services on CrOS (system-wide tracing).
     * Fixed filtering out of stale ftrace data that predates the beginning of
       the tracing session.
   Trace Processor:
     * Improved profile symbolizer. PERFETTO_SYMBOLIZER_MODE=index discovers
       symbol files by build id rather than name.
     * Added screen-state Android metrics.
   UI:
     * Added 'Info and stats' page to debug data losses and trace stats.
     * Added full cmdline to process detail panel.
     * Improved performance of async tracks using quantized queries.
     * Improved performance of counter and slice tracks for long traces by
       pre-caching quantized track data.
     * Improved actionablility of crash dialog when the Wasm module OOMs.


 v5.0 - 2020-07-01:
   Tracing service and probes:
     * Added gpu_mem_total ftrace event.
     * Added TrustZone (scm start/end) event.
     * Added protos for GPU memory tracking and updated render stages proto.
     * Added time_in_state probe for Android (CPU time broken down by frequency).

   Trace Processor:
     * Added ingestion of IRQ and SoftIRQ events.
     * Added ingestion of workqueue events. KAddr symbolization still missing.
     * Added ingestion of voltage regulators and board clock change events.
     * Added ingestion of new ION ion_buffer_create/destroy events.
     * Added ingestion of TrustZone (scm start/end) events.
     * Added SurfaceFlinger derived events (tracking of missed frames).
     * Changed parsing of scheduler task state on 4.14 kernels.
     * Changed importing of Java heap graphs: allow partial dumps.
     * Improved performance of the SQL query engine.

   UI:
     * Added dedicated query page for custom SQL queries.
     * Added navigation links for Binder slices.
     * Removed overview summary mode when zoomed out.
     * Fixed recording page when targeting Android P.
     * Improved slice pan/zoom performance by quantizing.
	Unreleased:
	Tracing service and probes:
	*
	Trace Processor:
	*
	UI:
	* Fixed ADB connection issues ("unable to reset device") on Windows and Mac.
	SDK:
	* Added support for writing track events using custom clock timestamps.


	v16.0 - 2021-06-01:
	Tracing service and probes:
	* Added support for building most targets (including traced, SDK and
	trace_processor_shell) from Windows using either clang-cl or MSVC 2019.
	* Added tracebox, a monolithic binary to capture traces with one command
	on Linux and older versions of Android (tested on Android Oreo).
	* Added support for service-side field-level filtering of traces. The
	consumer can pass a filter bytecode and ensure that non-allowed fields
	are never emitted in output.
	* Added reporting of service version and producer SDK version into the trace
	and `perfetto --query`.
	* Fixed compatibility with Android versions older than Pie (for sideloading)
	which cause failures when trying to enable atrace categories.
	Trace Processor:
	* Added new RPC interface based on a bidirectional binary pipe. This allows
	to simplify integration with out-of-process users. The existing --httpd
	interface now exposes a single /rpc endpoint. Older endpoints are still
	available for legacy clients.
	* Added support for counters and instant events in JSON traces.
	* Fixed support of displayTimeUnit in JSON traces.
	UI:
	* Added warning dialog when trying to use a trace_processor_shell --httpd
	which is too old.
	* Added warning dialog when trying to use a trace_processor_shell --httpd
	RPC instance from more than one tab.
	* Added links to convert the trace to JSON or systrace directly from the UI.
	* Changed track sorting logic. Tracks are now sorted in groups (e.g.,
	scheduling tracks, summary tracks, frame timeline tracks).
	* Fixed crashes happening flakily when pushing traces via window.open().


	v15.0 - 2021-05-05:
	Tracing service and probes:
	* Added support for {host,target}=aarch64 standalone builds.
	* Added --background cmdline switch to traced and traced_probes services.
	* Changed trigger_perfetto to ignore unknown command line arguments to
	preserve forward compatibility.
	* Added -a / --app cmdline argument to tools/record_android_trace.
	Trace Processor:
	* Added sanitisation of keys in nested debug annotation dictionaries.
	* Changed Android startup metric: count CPU time of JIT thread pool, report
	timestamp of activities during startup.
	* Changed android_surfaceflinger metric, added missed frame counters.
	* Changed version of SQLite to 3.35.4.
	* Fixed importing of JSON traces with decimal (sub-us) timestamp.
	* Fixed prepending "debug." prefix to debug annotations with non-interned
	names.
	UI:
	* Added support to visualize the lifetime of individual dmabuf allocations
	as async slices (datasource: already existing ftrace dmabuf event).
	* Fixed visualization of unfinished slices to extend to the end of the
	viewport.
	SDK:
	* Added support for passing arbitrary number of debug annotations to
	TRACE_EVENT and combining them with lambdas.
	* Added support for writing typed TrackEvent arguments using TRACE_EVENT
	inline without lambdas.
	* Changed ConvertTimestampToTraceTimeNs to be a member of
	TraceTimestampTraits<T> struct instead of a standalone function.
	* Changed TracedValue to use nested DebugAnnotation proto instead of
	DebugAnnotation::NestedValue.


	v14.0 - 2021-04-01:
	Tracing service and probes:
	* Added support for polling power rails on Android from the newer
	IPowerStats AIDL interface (previously using only the HAL interface).
	* Fixed native heap profiler crash when ABI of heapprofd and profiled
	process mismatch.
	* Changed encoding format of Anroid managed heap profiler to reduce heap
	dump sizes by delta-encoding object IDs.
	Trace Processor:
	* Added activity create/resume, layout inflation and resource timings to
	the Android startup metric.
	* Added chrome metadata key/value pairs (e.g. chrome version) into the
	`metadata` table with 'cr-' prefixed keys.
	* Added dma-buf-based memory metrics reporting total/avg/min/max dmabuf
	allocation per-dmabuf-heap and per-process.
	* Removed \|force_full_sort\| flag from config. This has been replaced
	by setting the sorting mode to force a full sort.
	UI:
	* Added tools/symbolize-ui-crash script to resolve crash reports via
	TypeScript source maps.
	* Fixed newlines when copying Android event log lines into the clipboard.
	* Fixed crash when selecting "Did not finish" slices.
	* Fixed OOM dialog to give actionable instructions when opening large traces
	rather than suggesting to file a bug.
	SDK:
	* Added /meson.build for bundling /sdk/perfetto.{cc,h} in Meson builds.
	* Added support for counter trace points with the TRACE_COUNTER macro.


	v13.0 - 2021-03-01:
	Tracing service and probes:
	* Added ability to sample callstacks using kernel tracepoints as timebase.
	* Added abililty to record the perf timebase counter values into the trace,
	both combined callstack+counter or counter-only.
	* Added abillity to trigger traces based on VM pressure on Android. Requires
	a dedicated tracing instance in $tracefs/instances/mm_events.
	Trace Processor:
	* Added sorting mode to trace processor config to specify how trace
	processor should sort events. The \|force_full_sort\| flag has been
	deprecated (with replacement) and will be removed in the next version.
	* Added ingestion of frame timeline events into the
	{expected,actual}_frame_timeline_slice tables.
	* Added support for Mali's trace_marker_write ftrace event.
	* Added memory metric based on newer android_fastrpc kernel events.
	UI:
	* Added flow events support for instant events and async tracks.
	* Added support for Android frame timeline events. They allow inspecting
	end-to-end expected vs actual app-to-surfaceflinger frame times.
	* Added ability to switch between Canary and Stable channels in the UI.
	* Added ability to drag&drop to open trace files.
	* Changed UI serving infrastructure, old ui versions can be now retrieved by
	directly opening https://ui.perfetto.dev/v12.1.269/ .
	* Removed thread state track for threads that have no activity.
	SDK:
	* Use process start time hashed with the process id as a unique process
	identifier, allowing multiple independent users of the SDK in the same
	process to interleave their events on shared tracks.
	* Record process and thread names into the trace.
	* Add ring buffer tracing support, i.e., periodic clearing of incremental
	state.
	Misc:
	* Convert python scripts to python3.


	v12.1 - 2021-02-01:
	Misc:
	* Fixed CHANGELOG which was missed in the 12.0 branch cut, causing
	mis-labeling of the version code in the v12.x branch as v11.0..N


	v12.0 - 2021-02-01:
	Tracing service and probes:
	* Added more helpful error messages if the client library is used without
	having been initialized.
	* Added //tools/record_android_trace script to facilitate recording traces
	from Android devices, automating start + stop-via-ctrl+c + pull + open.
	* Added auto-attachment of traces to Android bugreports if dumpstate is
	invoked when a trace with bugreport_score > 0 is running.
	SDK:
	* Added ability to customize the timestamp of events via
	ConvertTimestampToTraceTimeNs().
	* Fixed support for category names that contain a space.
	Trace Processor:
	* Added ingestion and query support for Android end-to-end frame timing
	events through the {actual, expected}_frame_timeline_slice tables.
	* Added time-to-reportFullyDrawn (Android's API) to startup metrics.
	* Fixed excessive memory usage when decoding traces containing callstacks
	(https://github.com/google/perfetto/issues/83).
	UI:
	* Added ability to inspect the full trace config string from the
	'Info and stats' page.
	* Fixed 'TABLE/VIEW XXX already exists' in the Metrics page when running the
	same metric twice.
	* Fixed sorting of tracks using numeric sorting instead of lexicographic:
	Thread {1, 2, 10, 11, 20} rather than Thread {1, 10, 11, 2, 20}.
	* Fixed CSP-related bug that was preventing the UI to work on Firefox.
	* Changed max zoom resolution to allow to zoom to sub-us events.


	v11.0 - 2021-01-01:
	Tracing service and probes:
	* Added trace packet interceptor API for rerouting trace data into
	non-Perfetto systems.
	* Added support for printing track events to the console.
	* Added a way to observe track event tracing sessions starting and
	stopping.
	Trace Processor:
	* Added "ancestor_slice" and "experimental_ancestor_stack_profile_callsite"
	table functions to look up ancestors of CPU stack samples in profiler
	tables.
	* Added power metric reporting suspend/resume time periods.
	UI:
	* Fixed CPU time calculation in example queries.
	* Added tracks to debug Android SystemUI jank.


	v10.0 - 2020-12-01:
	Tracing service and probes:
	* Fixed crash of tracing service if a client is unresponsive on the IPC
	channel. Clients are disconnected if they don't respond to IPCs for 10s.
	* Added cmdline arguments for integration within ChromeOS system image
	(--{producer,consumer}-socket-{group,mode} for chmod-ing sockets).
	* Changed path lookup logic for traced socket. /run/perfetto/ is used if the
	directory exists, falling back on /tmp/ otherwise.
	* Added support for kernel frame symbolization to the traced_perf callstack
	sampler.
	* Added support for resolving ftrace event arguments that require
	symbolization against printk_format.
	Trace Processor:
	* Added .read command to inject a SQL query file, similar to the -q cmdline.
	* Added trace-based metrics to root cause jank in Android System UI.
	* Added symbolization support for ELF files on Windows for heap and
	callstack profilers.
	* Added support for symbolizing names of workqueue ftrace events.
	* Improved Android startup metric with activity restart time.
	UI:
	* Added support for navigating flows with Ctrl+[ / Ctr+].
	* Improved query result panel, moved to the bottom group allowing
	simultaneous query result and timeline views.
	* Fixed data corruption when recording traces via the WebUSB-based Record
	page in the UI.


	v9.0 - 2020-11-01:
	Tracing service and probes:
	* Added support for recording traces from a system service through the
	client API.
	* The client library now reconnects producers automatically if the
	connection to the tracing service is lost. Also fixed crashes in ongoing
	tracing sessions when a disconnect occurs.
	* Added support for dpu and g2d ftrace events.
	* Enabled commit batching and producer side patching of chunks.
	* Add support for symbolizing kernel symbols for ftrace events.
	Trace Processor:
	* Fixed type affinity of string columns.
	UI:
	* Added initial support for running metrics from the UI.
	* Added support for displaying all flows when a slice or area is selected.
	* Highlight nodes that match the 'focus' string in the flamegraph.
	* Added search within slice args.
	* Fixed details panel height and moved query panel into details panel.
	* Enabled re-sharing of postMessage traces by echoing back the original URL.
	* Improved record page error messages.


	v8.0 - 2020-10-01:
	Tracing service and probes:
	* Added API for querying registered data sources and their capabilities.
	* Added support for profiling heap allocations on Linux via LD_PRELOAD.
	* Fixed possible race when initializing the consumer library.
	* Fixed subtle bugs on systems with 16KB system pages.
	Trace Processor:
	* Added a table which lists available metrics.
	* Added Python bindings on PyPi in the 'perfetto' package.
	* Added support for running trace_processor_shell on Android.
	* Added per-process metrics for GPU memory usage.
	* Added support for exporting flow events to JSON.
	* Added dynamic tables for navigating between slices of flows.
	UI:
	* Changed time marking: horizontal selection doesn't gray out anymore,
	pressing 'm' marks the range.
	* Added initial support for displaying flow event arrows.
	* Improved ordering of all thread tracks under process grouping.
	* Fixed UI crashes due to metric errors
	* Fixed selection of thread state slices.


	v7.0 - 2020-09-01:
	Tracing service and probes:
	* Added auto-reconnection to the SDK. Tracing::Initialize() now retries in
	the background, instead of failing, if the tracing service is unrechable.
	* Added support for recording cpuhp (CPU hotplug) ftrace events.
	* Fixed heap profiling unwinding on multi-ABI systems.
	* Fixed reporting of live objects in the native heap profiler when using
	--dump-at-max.
	* Fixed crash when writing trace events with field nesting level > 10.
	Trace Processor:
	* Added Python bindings, see
	https://perfetto.dev/docs/analysis/trace-processor#python-api .
	* Added ingestion for Chrome instant events and Chrome flow events.
	* Added ingestion for Android GPU memory events and sched_blocked_reason.
	* Added WebView power metric.
	* Added support for WSL1 where Async I/O is not available.
	* Improved detection of Android suspend/resume events.
	UI:
	* Added GPU memory recording controls and ingestion code. Requires a recent
	Android 12+ kernel.
	* Added details panel for flow events, showed when the user selects a slice
	involved in a flow (arrows in the UI are still being worked on).
	* Added instant events rendering.
	* Added Google Analytics.
	* Fixed I/O thread-states in 4.14 kernels to deal with the removal of
	wake-kill using sched_blocked_reason.
	* Fixed "Perfetto UI started debugging this browser" showing when opening
	the UI and the Chrome extension is installed.
	Misc:
	* Update language to comply with Android's inclusive language guidance.


	v6.0 - 2020-08-01:
	Tracing service and probes:
	* Added ftrace thermal events.
	* Added support for custom allocators to the heap profiler. Allows
	developers to report memory allocations that are not done through malloc.
	* Added detailed timestamping of key tracing session events.
	* Added support for building tracing services on CrOS (system-wide tracing).
	* Fixed filtering out of stale ftrace data that predates the beginning of
	the tracing session.
	Trace Processor:
	* Improved profile symbolizer. PERFETTO_SYMBOLIZER_MODE=index discovers
	symbol files by build id rather than name.
	* Added screen-state Android metrics.
	UI:
	* Added 'Info and stats' page to debug data losses and trace stats.
	* Added full cmdline to process detail panel.
	* Improved performance of async tracks using quantized queries.
	* Improved performance of counter and slice tracks for long traces by
	pre-caching quantized track data.
	* Improved actionablility of crash dialog when the Wasm module OOMs.


	v5.0 - 2020-07-01:
	Tracing service and probes:
	* Added gpu_mem_total ftrace event.
	* Added TrustZone (scm start/end) event.
	* Added protos for GPU memory tracking and updated render stages proto.
	* Added time_in_state probe for Android (CPU time broken down by frequency).

	Trace Processor:
	* Added ingestion of IRQ and SoftIRQ events.
	* Added ingestion of workqueue events. KAddr symbolization still missing.
	* Added ingestion of voltage regulators and board clock change events.
	* Added ingestion of new ION ion_buffer_create/destroy events.
	* Added ingestion of TrustZone (scm start/end) events.
	* Added SurfaceFlinger derived events (tracking of missed frames).
	* Changed parsing of scheduler task state on 4.14 kernels.
	* Changed importing of Java heap graphs: allow partial dumps.
	* Improved performance of the SQL query engine.

	UI:
	* Added dedicated query page for custom SQL queries.
	* Added navigation links for Binder slices.
	* Removed overview summary mode when zoomed out.
	* Fixed recording page when targeting Android P.
	* Improved slice pan/zoom performance by quantizing.