About **apitrace** ================== **apitrace** consists of a set of tools to: * trace OpenGL, OpenGL ES, Direct3D, and DirectDraw APIs calls to a file; * retrace 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.com/) for more details. Obtaining **apitrace** ====================== To obtain apitrace either [download the latest binaries](http://apitrace.github.com/#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 retrace application.trace Pass the `--sb` option to use a single buffered visual. Pass `--help` to `apitrace retrace` 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 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 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 ether 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 applications. There are some applications (e.g., Unigine Heaven, Android GPU emulator, etc.), that have global function pointers with the same name as GL entrypoints, living in a shared object that wasn't linked with `-Bsymbolic` flag, so relocations to those globals 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. To trace the application inside gdb, invoke gdb as: gdb --ex 'set exec-wrapper env LD_PRELOAD=/path/to/glxtrace.so' --args /path/to/application ### Android ### The following instructions should work at least for Android Ice Scream Sandwitch: For standalone applications the instructions above for Linux should work. To trace applications started from within the Android VM process (`app_process` aka zygote) you'll have to wrap this process and enable tracing dynamically for the application to be traced. - Wrapping the android main VM process: In the Android root /init.rc add the `LD_PRELOAD` setting to zygote's environment in the 'service zygote' section: service zygote ... setenv LD_PRELOAD /data/egltrace.so ... Note that ICS will overwrite the /init.rc during each boot with the version in the recovery image. So you'll have to change the file in your ICS source tree, rebuild and reflash the device. Rebuilding/reflashing only the recovery image should be sufficient. - Copy egltrace.so to /data On the host: adb push /path/to/apitrace/build/wrappers/egltrace.so /data - Adjust file permissions to store the trace file: By default egltrace.so will store the trace in `/data/app_process.trace`. For this to work for applications running with a uid other than 0, you have to allow writes to the `/data` directory on the device: chmod 0777 /data - Enable tracing for a specific process name: To trace for example the Settings application: setprop debug.apitrace.procname com.android.settings In general this name will match what `ps` reports. - Start the application: If the application was already running, for example due to ICS's way of pre-starting the apps, you might have to kill the application first: kill Launch the application for example from the application menu. ### Mac OS X ### Run the application you want to trace as DYLD_LIBRARY_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. 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 OpenGL applications you can embed annotations in the trace file through the [`GL_GREMEDY_string_marker`](http://www.opengl.org/registry/specs/GREMEDY/string_marker.txt) and [`GL_GREMEDY_frame_terminator`](http://www.opengl.org/registry/specs/GREMEDY/frame_terminator.txt) GL extensions. **apitrace** will advertise and intercept these GL extensions independently of the GL implementation. So all you have to do is to use these extensions when available. For example, if you use [GLEW](http://glew.sourceforge.net/) to dynamically detect and use GL extensions, you could easily accomplish this by doing: void foo() { if (GLEW_GREMEDY_string_marker) { glStringMarkerGREMEDY(0, __FUNCTION__ ": enter"); } ... if (GLEW_GREMEDY_string_marker) { glStringMarkerGREMEDY(0, __FUNCTION__ ": leave"); } } This has the added advantage of working equally well with gDEBugger. From OpenGL ES applications you can embed annotations in the trace file through the [`GL_EXT_debug_marker`](http://www.khronos.org/registry/gles/extensions/EXT/EXT_debug_marker.txt) extension. 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 GL state at a particular call ---------------------------------- You can get a dump of the bound GL state at call 12345 by doing: apitrace retrace -D 12345 application.trace > 12345.json This is precisely the mechanism the GUI obtains 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 ----------------------------- You can make a video of the output by doing apitrace dump-images -o - application.trace \ | ffmpeg -r 30 -f image2pipe -vcodec ppm -i pipe: -vcodec mpeg4 -y output.mp4 Trimming a trace ---------------- You can make a smaller trace by doing: apitrace trim --callset 100-1000 -o trimed.trace applicated.trace If you need precise control over which calls to trim you can specify the individual call numbers a plaintext file, as described in the 'Call sets' section above. 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 this can then be read by hand or analysed 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 retrace --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 GL 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 "$@" It is important that builds are both robust, and efficient. Due to broken dependency discovery in Mesa's makefile system, it was necessary invoke `make clean` in every iteration step. `ccache` should be installed to avoid recompiling unchanged source files. Then do: cd /path/to/mesa export LIBGL_DEBUG=verbose export LD_LIBRARY_PATH=$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 GL driver is unintentionally loaded due to 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 GL driver side-by-side. The latter can be either a previously known good build of the GL 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 GL 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/GL/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 [![githalytics.com alpha](https://cruel-carlota.pagodabox.com/c1062ad633aa7a458e9d7520021307e4 "githalytics.com")](http://githalytics.com/apitrace/apitrace)