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diff --git a/site/dev/contrib/testing.md b/site/dev/contrib/testing.md new file mode 100644 index 0000000000..c2ee8ed896 --- /dev/null +++ b/site/dev/contrib/testing.md @@ -0,0 +1,168 @@ +Correctness Testing +=================== + +Skia correctness testing is primarily served by a tool named DM. +This is a quickstart to building and running DM. + +~~~ +$ ./gyp_skia +$ ninja -C out/Debug dm +$ out/Debug/dm -v -w dm_output +~~~ + +When you run this, you may notice your CPU peg to 100% for a while, then taper +off to 1 or 2 active cores as the run finishes. This is intentional. DM is +very multithreaded, but some of the work, particularly GPU-backed work, is +still forced to run on a single thread. You can use --threads N to limit DM to +N threads if you like. This can sometimes be helpful on machines that have +relatively more CPU available than RAM. + +As DM runs, you ought to see a giant spew of output that looks something like this. +~~~ +Skipping nonrendering: Don't understand 'nonrendering'. +Skipping angle: Don't understand 'angle'. +Skipping nvprmsaa4: Could not create a surface. +492 srcs * 3 sinks + 382 tests == 1858 tasks + +( 25MB 1857) 1.36ms 8888 image mandrill_132x132_12x12.astc-5-subsets +( 25MB 1856) 1.41ms 8888 image mandrill_132x132_6x6.astc-5-subsets +( 25MB 1855) 1.35ms 8888 image mandrill_132x130_6x5.astc-5-subsets +( 25MB 1854) 1.41ms 8888 image mandrill_132x130_12x10.astc-5-subsets +( 25MB 1853) 151µs 8888 image mandrill_130x132_10x6.astc-5-subsets +( 25MB 1852) 154µs 8888 image mandrill_130x130_5x5.astc-5-subsets + ... +( 748MB 5) 9.43ms unit test GLInterfaceValidation +( 748MB 4) 30.3ms unit test HalfFloatTextureTest +( 748MB 3) 31.2ms unit test FloatingPointTextureTest +( 748MB 2) 32.9ms unit test DeferredCanvas_GPU +( 748MB 1) 49.4ms unit test ClipCache +( 748MB 0) 37.2ms unit test Blur +~~~ +Do not panic. + +As you become more familiar with DM, this spew may be a bit annoying. If you +remove -v from the command line, DM will spin its progress on a single line +rather than print a new line for each status update. + +Don't worry about the "Skipping something: Here's why." lines at startup. DM +supports many test configurations, which are not all appropriate for all +machines. These lines are a sort of FYI, mostly in case DM can't run some +configuration you might be expecting it to run. + +The next line is an overview of the work DM is about to do. +~~~ +492 srcs * 3 sinks + 382 tests == 1858 tasks +~~~ + +DM has found 382 unit tests (code linked in from tests/), and 492 other drawing +sources. These drawing sources may be GM integration tests (code linked in +from gm/), image files (from --images, which defaults to "resources") or .skp +files (from --skps, which defaults to "skps"). You can control the types of +sources DM will use with --src (default, "tests gm image skp"). + +DM has found 3 usable ways to draw those 492 sources. This is controlled by +--config, which today defaults to "565 8888 gpu nonrendering angle nvprmsaa4". +DM has skipped nonrendering, angle, and nvprmssa4, leaving three usable configs: +565, 8888, and gpu. These three name different ways to draw using Skia: + + - 565: draw using the software backend into a 16-bit RGB bitmap + - 8888: draw using the software backend into a 32-bit RGBA bitmap + - gpu: draw using the GPU backend (Ganesh) into a 32-bit RGBA bitmap + +Sometimes DM calls these configs, sometimes sinks. Sorry. There are many +possible configs but generally we pay most attention to 8888 and gpu. + +DM always tries to draw all sources into all sinks, which is why we multiply +492 by 3. The unit tests don't really fit into this source-sink model, so they +stand alone. A couple thousand tasks is pretty normal. Let's look at the +status line for one of those tasks. +~~~ +( 25MB 1857) 1.36ms 8888 image mandrill_132x132_12x12.astc-5-subsets +~~~ + +This status line tells us several things. + +First, it tells us that at the time we wrote the status line, the maximum +amount of memory DM had ever used was 25MB. Note this is a high water mark, +not the current memory usage. This is mostly useful for us to track on our +buildbots, some of which run perilously close to the system memory limit. + +Next, the status line tells us that there are 1857 unfinished tasks, either +currently running or waiting to run. We generally run one task per hardware +thread available, so on a typical laptop there are probably 4 or 8 running at +once. Sometimes the counts appear to show up out of order, particularly at DM +startup; it's harmless, and doesn't affect the correctness of the run. + +Next, we see this task took 1.36 milliseconds to run. Generally, the precision +of this timer is around 1 microsecond. The time is purely there for +informational purposes, to make it easier for us to find slow tests. + +Finally we see the configuration and name of the test we ran. We drew the test +"mandrill_132x132_12x12.astc-5-subsets", which is an "image" source, into an +"8888" sink. + +When DM finishes running, you should find a directory with file named dm.json, +and some nested directories filled with lots of images. +~~~ +$ ls dm_output +565 8888 dm.json gpu + +$ find dm_output -name '*.png' +dm_output/565/gm/3x3bitmaprect.png +dm_output/565/gm/aaclip.png +dm_output/565/gm/aarectmodes.png +dm_output/565/gm/alphagradients.png +dm_output/565/gm/arcofzorro.png +dm_output/565/gm/arithmode.png +dm_output/565/gm/astcbitmap.png +dm_output/565/gm/bezier_conic_effects.png +dm_output/565/gm/bezier_cubic_effects.png +dm_output/565/gm/bezier_quad_effects.png + ... +~~~ + +The directories are nested first by sink type (--config), then by source type (--src). +The image from the task we just looked at, "8888 image mandrill_132x132_12x12.astc-5-subsets", +can be found at dm_output/8888/image/mandrill_132x132_12x12.astc-5-subsets.png. + +dm.json is used by our automated testing system, so you can ignore it if you +like. It contains a listing of each test run and a checksum of the image +generated for that run. (Boring technical detail: it is not a checksum of the +.png file, but rather a checksum of the raw pixels used to create that .png.) + +Unit tests don't generally output anything but a status update when they pass. +If a test fails, DM will print out its assertion failures, both at the time +they happen and then again all together after everything is done running. +These failures are also included in the dm.json file. + +DM does not currently have a built-in image comparison facility, though we +might add one. For now, you can use the skdiff tool to compare corresponding +images from two runs of DM. +~~~ +$ ./gyp_skia +$ ninja -C out/Debug dm +$ out/Debug/dm -w good + + (do some work) + +$ ./gyp_skia +$ ninja -C out/Debug dm +$ out/Debug/dm -w bad + +$ ninja -C out/Debug skdiff +$ mkdir diff +$ out/Debug/skdiff good bad diff + + (open diff/index.html in your web browser) +~~~ + +That's the basics of DM. DM supports many other modes and flags. Here are a +few examples you might find handy. +~~~ +$ out/Debug/dm --help # Print all flags, their defaults, and a brief explanation of each. +$ out/Debug/dm --src tests # Run only unit tests. +$ out/Debug/dm --nocpu # Test only GPU-backed work. +$ out/Debug/dm --nogpu # Test only CPU-backed work. +$ out/Debug/dm --match blur # Run only work with "blur" in its name. +$ out/Debug/dm --dryRun # Don't really do anything, just print out what we'd do. +~~~ |