4941a2239e
Change-Id: I099f8a635df7dd0ddd3902459615250ea2c120c5 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/209874 Commit-Queue: Mike Klein <mtklein@google.com> Reviewed-by: Mike Klein <mtklein@google.com>
110 lines
4.1 KiB
Markdown
110 lines
4.1 KiB
Markdown
Tracing Skia Execution
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======================
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Introduction
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------------
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Skia is instrumented to provide execution traces in several ways. Within Chrome, Skia is traced
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with the standard [tracing interface](chrome://tracing), along with the rest of Chromium. In
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the Android framework, Skia's tracing is integrated into
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[atrace](https://source.android.com/devices/tech/debug/ftrace).
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For standalone builds, Skia's tools (DM, nanobench, and Viewer) are capable of tracing execution
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in three ways, controlled by the `--trace` command line argument.
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Standalone Tracing
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------------------
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Most arguments to `--trace` will be interpreted as a filename (the two exceptions are described
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below), and trace events will be written to that file in JSON format, suitable for viewing with
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[chrome://tracing](chrome://tracing).
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<!--?prettify lang=sh?-->
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# Run DM on several GMs to get tracing data
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out/Release/dm --config gl --match bleed --trace gl_bleed_gms.json
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This creates a file `gl_bleed_gms.json` in the current directory. There are limitations in Chrome's
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tracing tool that prevent loading a file larger than 256 MB. To stay under that limit (and avoid
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clutter and slowdown in the interface), it's best to run a small number of tests/benchmarks when
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tracing. Once you have generated a file in this way, go to
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[chrome://tracing](chrome://tracing), click Load:
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... then select the JSON file. The data will be loaded and can be navigated/inspected using the
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tracing tools. Tip: press '?' for a help screen explaining the available keyboard and mouse
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controls.
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Android ATrace
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--------------
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Running any tool with `--trace atrace` on an Android device will cause the application to forward
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tracing information to [atrace](https://source.android.com/devices/tech/debug/ftrace). On other
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platforms, this has no effect.
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If you run `systrace` from the host command line, you will need to supply `-a <app_name>`,
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and the `<app_name>` argument will need to exactly match the command line used on the target
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device. For example, if you use `adb shell "cd /data/local/tmp; ./nanobench --trace atrace ..."`
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you must pass `-a ./nanobench` or systrace will ignore events from the application.
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Console Logging
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---------------
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For simple situations, all tracing events can be directed to the console with `--trace debugf`:
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<!--?prettify lang=sh?-->
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# Run DM on a single GM with SkDebugf tracing
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out/Release/dm --config gl --match ^gamma$ --trace debugf
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~~~
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[ 0] <skia.gpu> GrDrawingManager::internalFlush id=1 #0 {
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[ 0] } GrDrawingManager::internalFlush
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[ 0] <skia.gpu> GrGpu::createTexture id=1 #1 {
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[ 0] } GrGpu::createTexture
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[ 0] <skia.gpu> GrRenderTargetContext::discard id=1 #2 {
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[ 0] } GrRenderTargetContext::discard
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[ 0] <skia.gpu> SkGpuDevice::clearAll id=1 #3 {
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[ 1] <skia.gpu> GrRenderTargetContext::clear id=1 #4 {
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[ 1] } GrRenderTargetContext::clear
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[ 0] } SkGpuDevice::clearAll
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[ 0] <skia> SkCanvas::drawRect() #5 {
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[ 1] <skia.gpu> SkGpuDevice::drawRect id=1 #6 {
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[ 2] <skia.gpu> GrRenderTargetContext::drawRect id=1 #7 {
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[ 3] <skia.gpu> GrRenderTargetContext::addDrawOp id=1 #8 {
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[ 3] } GrRenderTargetContext::addDrawOp
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[ 2] } GrRenderTargetContext::drawRect
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[ 1] } SkGpuDevice::drawRect
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[ 0] } SkCanvas::drawRect()
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...
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~~~
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Adding More Trace Events
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------------------------
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Adding more trace events involves using a set of `TRACE_` macros. The simplest example, to record
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the time spent in a function or other scope, is:
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~~~
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#include "SkTraceEvent.h"
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...
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void doSomething() {
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// Add an event for the duration of the current function (or other scope)
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// "skia" is a category name, for filtering events while recording
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// TRACE_FUNC is the event name, and expands to the name of the current function
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TRACE_EVENT0("skia", TRACE_FUNC);
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if (doExtraWork) {
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TRACE_EVENT0("skia", "ExtraWorkBeingDone");
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...
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}
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}
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~~~
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For more examples, including other kinds of trace events and attaching parameters to events, see
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the comments in
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[SkTraceEventCommon.h](https://cs.chromium.org/chromium/src/third_party/skia/src/core/SkTraceEventCommon.h).
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