About **apitrace** ================== **apitrace** consists of a set of tools to: * trace OpenGL, OpenGL ES, Direct3D, and DirectDraw APIs calls to a file; * replay OpenGL and OpenGL ES calls from a file; * inspect OpenGL state at any call while retracing; * visualize and edit trace files. See the [apitrace homepage](http://apitrace.github.io/) for more details. Obtaining **apitrace** ====================== To obtain apitrace either [download the latest binaries](http://apitrace.github.io/#download) for your platform if available, or follow the instructions in INSTALL.markdown to build it yourself. On 64bits Linux and Windows platforms you'll need apitrace binaries that match the architecture (32bits or 64bits) of the application being traced. Basic usage =========== Run the application you want to trace as apitrace trace --api API /path/to/application [args...] and it will generate a trace named `application.trace` in the current directory. You can specify the written trace filename by passing the `--output` command line option. Problems while tracing (e.g, if the application uses calls/parameters unsupported by apitrace) will be reported via stderr output on Unices. On Windows you'll need to run [DebugView](http://technet.microsoft.com/en-us/sysinternals/bb896647) to view these messages. Follow the "Tracing manually" instructions below if you cannot obtain a trace. View the trace with apitrace dump application.trace Replay an OpenGL trace with apitrace replay application.trace Pass the `--sb` option to use a single buffered visual. Pass `--help` to `apitrace replay` for more options. Basic GUI usage =============== Start the GUI as qapitrace application.trace You can also tell the GUI to go directly to a specific call qapitrace application.trace 12345 Backtrace Capturing =================== apitrace now has the ability to capture the call stack to an OpenGL call. This can be helpful in determing which piece of code made that glDrawArrays call. *NOTE* this feature is currently only available on Android and Linux at the moment. On linux you need to have libunwind, and libdwarf installed to compile in the feature. To use the feature you need to set an environment variable with the list of GL call prefixes you wish to capture stack traces to. export APITRACE_BACKTRACE="glDraw* glUniform*" The backtrace data will show up in qapitrace in the bottom section as a new tab. Advanced command line usage =========================== Call sets --------- Several tools take `CALLSET` arguments, e.g: apitrace dump --calls=CALLSET foo.trace apitrace dump-images --calls=CALLSET foo.trace apitrace trim --calls=CALLSET1 --calls=CALLSET2 foo.trace The call syntax is very flexible. Here are a few examples: * `4` one call * `0,2,4,5` set of calls * `"0 2 4 5"` set of calls (commas are optional and can be replaced with whitespace) * `0-100/2` calls 1, 3, 5, ..., 99 * `0-1000/draw` all draw calls between 0 and 1000 * `0-1000/fbo` all fbo changes between calls 0 and 1000 * `frame` all calls at end of frames * `@foo.txt` read call numbers from `foo.txt`, using the same syntax as above Tracing manually ---------------- ### Linux ### On 64 bits systems, you'll need to determine whether the application is 64 bits or 32 bits. This can be done by doing file /path/to/application But beware of wrapper shell scripts -- what matters is the architecture of the main process. Run the GLX application you want to trace as LD_PRELOAD=/path/to/apitrace/wrappers/glxtrace.so /path/to/application and it will generate a trace named `application.trace` in the current directory. You can specify the written trace filename by setting the `TRACE_FILE` environment variable before running. For EGL applications you will need to use `egltrace.so` instead of `glxtrace.so`. The `LD_PRELOAD` mechanism should work with the majority of applications. There are some applications (e.g., Unigine Heaven, Android GPU emulator, etc.), that have global function pointers with the same name as OpenGL entrypoints, living in a shared object that wasn't linked with `-Bsymbolic` flag, so relocations to those global function pointers get overwritten with the address to our wrapper library, and the application will segfault when trying to write to them. For these applications it is possible to trace by using `glxtrace.so` as an ordinary `libGL.so` and injecting it via `LD_LIBRARY_PATH`: ln -s glxtrace.so wrappers/libGL.so ln -s glxtrace.so wrappers/libGL.so.1 ln -s glxtrace.so wrappers/libGL.so.1.2 export LD_LIBRARY_PATH=/path/to/apitrace/wrappers:$LD_LIBRARY_PATH export TRACE_LIBGL=/path/to/real/libGL.so.1 /path/to/application If you are an application developer, you can avoid this either by linking with `-Bsymbolic` flag, or by using some unique prefix for your function pointers. See the `ld.so` man page for more information about `LD_PRELOAD` and `LD_LIBRARY_PATH` environment flags. ### Android ### To trace standalone native OpenGL ES applications, use `LD_PRELOAD=/path/to/egltrace.so /path/to/application` as described in the previous section. To trace Java applications, refer to Dalvik.markdown. ### Mac OS X ### Run the application you want to trace as DYLD_FRAMEWORK_PATH=/path/to/apitrace/wrappers /path/to/application Note that although Mac OS X has an `LD_PRELOAD` equivalent, `DYLD_INSERT_LIBRARIES`, it is mostly useless because it only works with `DYLD_FORCE_FLAT_NAMESPACE=1` which breaks most applications. See the `dyld` man page for more details about these environment flags. ### Windows ### When tracing third-party applications, you can identify the target application's main executable, either by: * right clicking on the application's icon in the _Start Menu_, choose _Properties_, and see the _Target_ field; * or by starting the application, run Windows Task Manager (taskmgr.exe), right click on the application name in the _Applications_ tab, choose _Go To Process_, note the highlighted _Image Name_, and search it on `C:\Program Files` or `C:\Program Files (x86)`. On 64 bits Windows, you'll need to determine ether the application is a 64 bits or 32 bits. 32 bits applications will have a `*32` suffix in the _Image Name_ column of the _Processes_ tab of _Windows Task Manager_ window. You also need to know which graphics API is being used. If you are unsure, the simplest way to determine what API an application uses is to: * download and run [Process Explorer](http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx) * search and select the application's process in _Process Explorer_ * list the DLLs by pressing `Ctrl + D` * sort DLLs alphabetically, and look for the DLLs such as `opengl32.dll`, `d3d9.dll`, `d3d10.dll`, etc. Copy the appropriate `opengl32.dll`, `d3d8.dll`, or `d3d9.dll` from the wrappers directory to the directory with the application you want to trace. Then run the application as usual. You can specify the written trace filename by setting the `TRACE_FILE` environment variable before running. For D3D10 and higher you really must use `apitrace trace -a DXGI ...`. This is because D3D10-11 API span many DLLs which depend on each other, and once a DLL with a given name is loaded Windows will reuse it for LoadLibrary calls of the same name, causing internal calls to be traced erroneously. `apitrace trace` solves this issue by injecting a DLL `dxgitrace.dll` and patching all modules to hook only the APIs of interest. Emitting annotations to the trace --------------------------------- From within OpenGL applications you can embed annotations in the trace file through the following extensions: * [`GL_KHR_debug`](http://www.opengl.org/registry/specs/KHR/debug.txt) * [`GL_ARB_debug_output`](http://www.opengl.org/registry/specs/ARB/debug_output.txt) * [`GL_EXT_debug_marker`](http://www.khronos.org/registry/gles/extensions/EXT/EXT_debug_marker.txt) * [`GL_EXT_debug_label`](http://www.opengl.org/registry/specs/EXT/EXT_debug_label.txt) * [`GL_AMD_debug_output`](http://www.opengl.org/registry/specs/AMD/debug_output.txt) * [`GL_GREMEDY_string_marker`](http://www.opengl.org/registry/specs/GREMEDY/string_marker.txt) * [`GL_GREMEDY_frame_terminator`](http://www.opengl.org/registry/specs/GREMEDY/frame_terminator.txt) **apitrace** will advertise and intercept these OpenGL extensions regardless of whether the OpenGL implementation supports them or not. So all you have to do is to use these extensions when available, and you can be sure they will be available when tracing inside **apitrace**. For example, if you use [GLEW](http://glew.sourceforge.net/) to dynamically detect and use OpenGL extensions, you could easily accomplish this by doing: void foo() { if (GLEW_KHR_debug) { glPushDebugGroup(GL_DEBUG_SOURCE_APPLICATION, 0, -1, __FUNCTION__); } ... if (GLEW_KHR_debug) { glDebugMessageInsert(GL_DEBUG_SOURCE_APPLICATION, GL_DEBUG_TYPE_OTHER, 0, GL_DEBUG_SEVERITY_MEDIUM, -1, "bla bla"); } ... if (GLEW_KHR_debug) { glPopDebugGroup(); } } This has the added advantage of working equally well with other OpenGL debugging tools. Also, provided that the OpenGL implementation supports `GL_KHR_debug`, labels defined via glObjectLabel() , and the labels of several objects (textures, framebuffers, samplers, etc. ) will appear in the GUI state dumps, in the parameters tab. For OpenGL ES applications you can embed annotations in the trace file through the [`GL_KHR_debug`](http://www.khronos.org/registry/gles/extensions/KHR/debug.txt) or [`GL_EXT_debug_marker`](http://www.khronos.org/registry/gles/extensions/EXT/EXT_debug_marker.txt) extensions. For Direct3D applications you can follow the standard procedure for [adding user defined events to Visual Studio Graphics Debugger / PIX](http://msdn.microsoft.com/en-us/library/vstudio/hh873200.aspx): - `D3DPERF_BeginEvent`, `D3DPERF_EndEvent`, and `D3DPERF_SetMarker` for D3D9 applications. - `ID3DUserDefinedAnnotation::BeginEvent`, `ID3DUserDefinedAnnotation::EndEvent`, and `ID3DUserDefinedAnnotation::SetMarker` for D3D11.1 applications. Dump OpenGL state at a particular call ---------------------------------- You can get a dump of the bound OpenGL state at call 12345 by doing: apitrace replay -D 12345 application.trace > 12345.json This is precisely the mechanism the GUI uses to obtain its own state. You can compare two state dumps by doing: apitrace diff-state 12345.json 67890.json Comparing two traces side by side --------------------------------- apitrace diff trace1.trace trace2.trace This works only on Unices, and it will truncate the traces due to performance limitations. Recording a video with FFmpeg/Libav ----------------------------------- You can make a video of the output with FFmpeg by doing apitrace dump-images -o - application.trace \ | ffmpeg -r 30 -f image2pipe -vcodec ppm -i pipe: -vcodec mpeg4 -y output.mp4 or Libav (which replaces FFmpeg on recent Debian/Ubuntu distros) doing apitrace dump-images -o - application.trace \ | avconv -r 30 -f image2pipe -vcodec ppm -i - -vcodec mpeg4 -y output.mp4 Recording a video with gstreamer -------------------------------------- You can make a video of the output with gstreamer by doing glretrace --snapshot-format=RGB -s - smokinguns.trace | gst-launch-0.10 fdsrc blocksize=409600 ! queue \ ! videoparse format=rgb width=1920 height=1080 ! queue ! ffmpegcolorspace ! queue \ ! vaapiupload direct-rendering=0 ! queue ! vaapiencodeh264 ! filesink location=xxx.264 Trimming a trace ---------------- You can truncate a trace by doing: apitrace trim --exact --calls 0-12345 -o trimed.trace application.trace If you need precise control over which calls to trim you can specify the individual call numbers in a plain text file, as described in the 'Call sets' section above. There is also experimental support for automatically trimming the calls necessary for a given frame or call: apitrace trim --auto --calls=12345 -o trimed.trace application.trace apitrace trim --auto --frames=12345 -o trimed.trace application.trace Profiling a trace ----------------- You can perform gpu and cpu profiling with the command line options: * `--pgpu` record gpu times for frames and draw calls. * `--pcpu` record cpu times for frames and draw calls. * `--ppd` record pixels drawn for each draw call. The results from these can then be read by hand or analyzed with a script. `scripts/profileshader.py` will read the profile results and format them into a table which displays profiling results per shader. For example, to record all profiling data and utilise the per shader script: apitrace replay --pgpu --pcpu --ppd foo.trace | ./scripts/profileshader.py Advanced usage for OpenGL implementors ====================================== There are several advanced usage examples meant for OpenGL implementors. Regression testing ------------------ These are the steps to create a regression test-suite around **apitrace**: * obtain a trace * obtain reference snapshots, by doing on a reference system: mkdir /path/to/reference/snapshots/ apitrace dump-images -o /path/to/reference/snapshots/ application.trace * prune the snapshots which are not interesting * to do a regression test, use `apitrace diff-images`: apitrace dump-images -o /path/to/test/snapshots/ application.trace apitrace diff-images --output summary.html /path/to/reference/snapshots/ /path/to/test/snapshots/ Automated git-bisection ----------------------- With tracecheck.py it is possible to automate git bisect and pinpoint the commit responsible for a regression. Below is an example of using tracecheck.py to bisect a regression in the Mesa-based Intel 965 driver. But the procedure could be applied to any OpenGL driver hosted on a git repository. First, create a build script, named build-script.sh, containing: #!/bin/sh set -e export PATH=/usr/lib/ccache:$PATH export CFLAGS='-g' export CXXFLAGS='-g' ./autogen.sh --disable-egl --disable-gallium --disable-glut --disable-glu --disable-glw --with-dri-drivers=i965 make clean make "$@" It is important that builds are both robust, and efficient. Due to broken dependency discovery in Mesa's makefile system, it was necessary to invoke `make clean` in every iteration step. `ccache` should be installed to avoid recompiling unchanged source files. Then do: cd /path/to/mesa export LIBGL_DEBUG=verbose export LD_LIBRARY_PATH=$PWD/lib export LIBGL_DRIVERS_DIR=$PWD/lib git bisect start \ 6491e9593d5cbc5644eb02593a2f562447efdcbb 71acbb54f49089b03d3498b6f88c1681d3f649ac \ -- src/mesa/drivers/dri/intel src/mesa/drivers/dri/i965/ git bisect run /path/to/tracecheck.py \ --precision-threshold 8.0 \ --build /path/to/build-script.sh \ --gl-renderer '.*Mesa.*Intel.*' \ --retrace=/path/to/glretrace \ -c /path/to/reference/snapshots/ \ topogun-1.06-orc-84k.trace The trace-check.py script will skip automatically when there are build failures. The `--gl-renderer` option will also cause a commit to be skipped if the `GL_RENDERER` is unexpected (e.g., when a software renderer or another OpenGL driver is unintentionally loaded due to a missing symbol in the DRI driver, or another runtime fault). Side by side retracing ---------------------- In order to determine which draw call a regression first manifests one could generate snapshots for every draw call, using the `-S` option. That is, however, very inefficient for big traces with many draw calls. A faster approach is to run both the bad and a good OpenGL driver side-by-side. The latter can be either a previously known good build of the OpenGL driver, or a reference software renderer. This can be achieved with retracediff.py script, which invokes glretrace with different environments, allowing to choose the desired OpenGL driver by manipulating variables such as `LD_LIBRARY_PATH`, `LIBGL_DRIVERS_DIR`, or `TRACE_LIBGL`. For example, on Linux: ./scripts/retracediff.py \ --ref-env LD_LIBRARY_PATH=/path/to/reference/OpenGL/implementation \ --retrace /path/to/glretrace \ --diff-prefix=/path/to/output/diffs \ application.trace Or on Windows: python scripts\retracediff.py --retrace \path\to\glretrace.exe --ref-env TRACE_LIBGL=\path\to\reference\opengl32.dll application.trace Advanced GUI usage ================== qapitrace has rudimentary support for replaying traces on a remote target device. This can be useful, for example, when developing for an embedded system. The primary GUI will run on the local host, while any replays will be performed on the target device. In order to target a remote device, use the command-line: qapitrace --remote-target In order for this to work, the following must be available in the system configuration: 1. It must be possible for the current user to initiate an ssh session that has access to the target's window system. The command to be exectuted by qapitrace will be: ssh glretrace For example, if the target device is using the X window system, one can test whether an ssh session has access to the target X server with: ssh xdpyinfo If this command fails with something like "cannot open display" then the user will have to configure the target to set the DISPLAY environment variable, (for example, setting DISPLAY=:0 in the .bashrc file on the target or similar). Also, note that if the ssh session requires a custom username, then this must be configured on the host side so that ssh can be initiated without a username. For example, if you normally connect with `ssh user@192.168.0.2` you could configure ~/.ssh/config on the host with a block such as: Host target HostName 192.168.0.2 User user And after this you should be able to connect with `ssh target` so that you can also use `qapitrace --remote-target target`. 2. The target host must have a functional glretrace binary available 3. The target host must have access to at the same path in the filesystem as the path on the host system being passed to the qapitrace command line.