281bf5249c
BUG=skia: Preview link: http://skiadocs.com:8000/dev/testing/?cl=954523004 Review URL: https://codereview.chromium.org/954523004
182 lines
7.3 KiB
Markdown
182 lines
7.3 KiB
Markdown
Correctness Testing
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===================
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Skia correctness testing is primarily served by a tool named DM.
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This is a quickstart to building and running DM.
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~~~
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$ ./gyp_skia
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$ ninja -C out/Debug dm
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$ out/Debug/dm -v -w dm_output
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~~~
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When you run this, you may notice your CPU peg to 100% for a while, then taper
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off to 1 or 2 active cores as the run finishes. This is intentional. DM is
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very multithreaded, but some of the work, particularly GPU-backed work, is
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still forced to run on a single thread. You can use `--threads N` to limit DM to
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N threads if you like. This can sometimes be helpful on machines that have
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relatively more CPU available than RAM.
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As DM runs, you ought to see a giant spew of output that looks something like this.
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~~~
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Skipping nonrendering: Don't understand 'nonrendering'.
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Skipping angle: Don't understand 'angle'.
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Skipping nvprmsaa4: Could not create a surface.
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492 srcs * 3 sinks + 382 tests == 1858 tasks
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( 25MB 1857) 1.36ms 8888 image mandrill_132x132_12x12.astc-5-subsets
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( 25MB 1856) 1.41ms 8888 image mandrill_132x132_6x6.astc-5-subsets
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( 25MB 1855) 1.35ms 8888 image mandrill_132x130_6x5.astc-5-subsets
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( 25MB 1854) 1.41ms 8888 image mandrill_132x130_12x10.astc-5-subsets
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( 25MB 1853) 151µs 8888 image mandrill_130x132_10x6.astc-5-subsets
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( 25MB 1852) 154µs 8888 image mandrill_130x130_5x5.astc-5-subsets
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...
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( 748MB 5) 9.43ms unit test GLInterfaceValidation
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( 748MB 4) 30.3ms unit test HalfFloatTextureTest
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( 748MB 3) 31.2ms unit test FloatingPointTextureTest
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( 748MB 2) 32.9ms unit test DeferredCanvas_GPU
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( 748MB 1) 49.4ms unit test ClipCache
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( 748MB 0) 37.2ms unit test Blur
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~~~
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Do not panic.
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As you become more familiar with DM, this spew may be a bit annoying. If you
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remove -v from the command line, DM will spin its progress on a single line
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rather than print a new line for each status update.
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Don't worry about the "Skipping something: Here's why." lines at startup. DM
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supports many test configurations, which are not all appropriate for all
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machines. These lines are a sort of FYI, mostly in case DM can't run some
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configuration you might be expecting it to run.
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The next line is an overview of the work DM is about to do.
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~~~
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492 srcs * 3 sinks + 382 tests == 1858 tasks
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~~~
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DM has found 382 unit tests (code linked in from tests/), and 492 other drawing
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sources. These drawing sources may be GM integration tests (code linked in
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from gm/), image files (from `--images`, which defaults to "resources") or .skp
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files (from `--skps`, which defaults to "skps"). You can control the types of
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sources DM will use with `--src` (default, "tests gm image skp").
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DM has found 3 usable ways to draw those 492 sources. This is controlled by
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`--config`, which today defaults to "565 8888 gpu nonrendering angle nvprmsaa4".
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DM has skipped nonrendering, angle, and nvprmssa4, leaving three usable configs:
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565, 8888, and gpu. These three name different ways to draw using Skia:
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- 565: draw using the software backend into a 16-bit RGB bitmap
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- 8888: draw using the software backend into a 32-bit RGBA bitmap
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- gpu: draw using the GPU backend (Ganesh) into a 32-bit RGBA bitmap
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Sometimes DM calls these configs, sometimes sinks. Sorry. There are many
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possible configs but generally we pay most attention to 8888 and gpu.
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DM always tries to draw all sources into all sinks, which is why we multiply
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492 by 3. The unit tests don't really fit into this source-sink model, so they
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stand alone. A couple thousand tasks is pretty normal. Let's look at the
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status line for one of those tasks.
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~~~
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( 25MB 1857) 1.36ms 8888 image mandrill_132x132_12x12.astc-5-subsets
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~~~
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This status line tells us several things.
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First, it tells us that at the time we wrote the status line, the maximum
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amount of memory DM had ever used was 25MB. Note this is a high water mark,
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not the current memory usage. This is mostly useful for us to track on our
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buildbots, some of which run perilously close to the system memory limit.
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Next, the status line tells us that there are 1857 unfinished tasks, either
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currently running or waiting to run. We generally run one task per hardware
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thread available, so on a typical laptop there are probably 4 or 8 running at
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once. Sometimes the counts appear to show up out of order, particularly at DM
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startup; it's harmless, and doesn't affect the correctness of the run.
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Next, we see this task took 1.36 milliseconds to run. Generally, the precision
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of this timer is around 1 microsecond. The time is purely there for
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informational purposes, to make it easier for us to find slow tests.
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Finally we see the configuration and name of the test we ran. We drew the test
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"mandrill_132x132_12x12.astc-5-subsets", which is an "image" source, into an
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"8888" sink.
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When DM finishes running, you should find a directory with file named dm.json,
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and some nested directories filled with lots of images.
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~~~
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$ ls dm_output
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565 8888 dm.json gpu
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$ find dm_output -name '*.png'
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dm_output/565/gm/3x3bitmaprect.png
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dm_output/565/gm/aaclip.png
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dm_output/565/gm/aarectmodes.png
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dm_output/565/gm/alphagradients.png
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dm_output/565/gm/arcofzorro.png
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dm_output/565/gm/arithmode.png
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dm_output/565/gm/astcbitmap.png
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dm_output/565/gm/bezier_conic_effects.png
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dm_output/565/gm/bezier_cubic_effects.png
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dm_output/565/gm/bezier_quad_effects.png
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...
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~~~
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The directories are nested first by sink type (`--config`), then by source type (`--src`).
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The image from the task we just looked at, "8888 image mandrill_132x132_12x12.astc-5-subsets",
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can be found at dm_output/8888/image/mandrill_132x132_12x12.astc-5-subsets.png.
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dm.json is used by our automated testing system, so you can ignore it if you
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like. It contains a listing of each test run and a checksum of the image
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generated for that run. (Boring technical detail: it is not a checksum of the
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.png file, but rather a checksum of the raw pixels used to create that .png.)
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Unit tests don't generally output anything but a status update when they pass.
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If a test fails, DM will print out its assertion failures, both at the time
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they happen and then again all together after everything is done running.
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These failures are also included in the dm.json file.
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DM has a simple facility to compare against the results of a previous run:
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~~~
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$ ./gyp_skia
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$ ninja -C out/Debug dm
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$ out/Debug/dm -w good
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(do some work)
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$ ./gyp_skia
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$ ninja -C out/Debug dm
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$ out/Debug/dm -r good -w bad
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~~~
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When using `-r`, DM will display a failure for any test that didn't produce the
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same image as the `good` run.
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For anything fancier, I suggest using skdiff:
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~~~
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$ ./gyp_skia
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$ ninja -C out/Debug dm
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$ out/Debug/dm -w good
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(do some work)
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$ ./gyp_skia
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$ ninja -C out/Debug dm
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$ out/Debug/dm -w bad
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$ ninja -C out/Debug skdiff
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$ mkdir diff
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$ out/Debug/skdiff good bad diff
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(open diff/index.html in your web browser)
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~~~
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That's the basics of DM. DM supports many other modes and flags. Here are a
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few examples you might find handy.
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~~~
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$ out/Debug/dm --help # Print all flags, their defaults, and a brief explanation of each.
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$ out/Debug/dm --src tests # Run only unit tests.
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$ out/Debug/dm --nocpu # Test only GPU-backed work.
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$ out/Debug/dm --nogpu # Test only CPU-backed work.
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$ out/Debug/dm --match blur # Run only work with "blur" in its name.
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$ out/Debug/dm --dryRun # Don't really do anything, just print out what we'd do.
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~~~
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