[libcamera-devel] [PATCH 2/2] test: v4l2_videodevice: Add test for V4L2BufferCache
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Tue Feb 18 00:38:51 CET 2020
Hello,
On Mon, Feb 17, 2020 at 01:46:14PM +0100, Niklas Söderlund wrote:
> On 2020-02-17 10:12:30 +0000, Kieran Bingham wrote:
> > On 16/02/2020 16:16, Niklas Söderlund wrote:
> >> Add test to test the different modes and situations the V4L2BufferCache
> >> can be put to. The tests verify that a FrameBuffer used with the cache
> >> results in a V4L2 video device index can be resolved, and that the cache
> >> implementation is capable of keeping buffers in a hot state.
> >>
> >> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> >> ---
> >> test/v4l2_videodevice/buffer_cache.cpp | 286 +++++++++++++++++++++++++
> >> test/v4l2_videodevice/meson.build | 1 +
> >> 2 files changed, 287 insertions(+)
> >> create mode 100644 test/v4l2_videodevice/buffer_cache.cpp
> >>
> >> diff --git a/test/v4l2_videodevice/buffer_cache.cpp b/test/v4l2_videodevice/buffer_cache.cpp
> >> new file mode 100644
> >> index 0000000000000000..6244361130525d29
> >> --- /dev/null
> >> +++ b/test/v4l2_videodevice/buffer_cache.cpp
> >> @@ -0,0 +1,286 @@
> >> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> >> +/*
> >> + * Copyright (C) 2020, Google Inc.
> >> + *
> >> + * Test the buffer cache different operation modes
> >> + */
> >> +
> >> +#include <iostream>
> >> +#include <random>
> >> +#include <vector>
> >> +
> >> +#include <libcamera/stream.h>
> >> +
> >> +#include "device_enumerator.h"
> >> +#include "media_device.h"
> >> +#include "v4l2_videodevice.h"
> >> +
> >> +#include "test.h"
> >> +
> >> +using namespace libcamera;
> >> +
> >> +namespace {
> >> +
> >> +/* A provider of source of external buffers, suitable for to use by V4L2BufferCache. */
> >> +class BufferSource
> >> +{
> >> +public:
> >> + BufferSource()
> >> + : video_(nullptr)
> >> + {
> >> + }
> >> +
> >> + ~BufferSource()
> >> + {
> >> + if (video_) {
> >> + video_->releaseBuffers();
> >> + video_->close();
> >> + }
> >> +
> >> + delete video_;
> >> + video_ = nullptr;
> >> +
> >> + if (media_)
> >> + media_->release();
> >> + }
> >> +
> >> + int allocate(const StreamConfiguration &config)
> >> + {
> >> + /* Locate and open the video device. */
> >> + std::string videoDeviceName = "vivid-000-vid-out";
> >> +
> >> + std::unique_ptr<DeviceEnumerator> enumerator =
> >> + DeviceEnumerator::create();
> >> + if (!enumerator) {
> >> + std::cout << "Failed to create device enumerator" << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + if (enumerator->enumerate()) {
> >> + std::cout << "Failed to enumerate media devices" << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + DeviceMatch dm("vivid");
> >> + dm.add(videoDeviceName);
> >> +
> >> + media_ = enumerator->search(dm);
> >> + if (!media_) {
> >> + std::cout << "No vivid output device available" << std::endl;
> >> + return TestSkip;
> >> + }
> >> +
> >> + video_ = V4L2VideoDevice::fromEntityName(media_.get(), videoDeviceName);
> >> + if (!video_) {
> >> + std::cout << "Unable to open " << videoDeviceName << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + if (video_->open())
> >> + return TestFail;
> >> +
> >> + /* Configure the format. */
> >> + V4L2DeviceFormat format;
> >> + if (video_->getFormat(&format)) {
> >> + std::cout << "Failed to get format on output device" << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + format.size = config.size;
> >> + format.fourcc = V4L2VideoDevice::toV4L2Fourcc(config.pixelFormat, false);
> >> + if (video_->setFormat(&format)) {
> >> + std::cout << "Failed to set format on output device" << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + if (video_->exportBuffers(config.bufferCount, &buffers_) < 0) {
> >> + std::cout << "Failed to export buffers" << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + return TestPass;
> >> + }
> >> +
> >> + const std::vector<std::unique_ptr<FrameBuffer>> &buffers()
> >> + {
> >> + return buffers_;
> >> + }
> >> +
> >> +private:
> >> + std::shared_ptr<MediaDevice> media_;
> >> + V4L2VideoDevice *video_;
> >> + std::vector<std::unique_ptr<FrameBuffer>> buffers_;
> >> +};
> >> +
> >> +class BufferCacheTest : public Test
> >> +{
> >> +public:
> >> + /*
> >> + * Test that a cache with the same size as there are buffers results in
> >> + * a sequential run over; 0, 1, 2, 3, 4, 0, 1, 2, 3, 4, ...
> >> + *
> >> + * Test only valid when the cache size is as least as big as there are
> >> + * number of buffers.
> >> + */
> >> + int testSequential(V4L2BufferCache *cache,
> >> + const std::vector<std::unique_ptr<FrameBuffer>> &buffers)
> >> + {
> >> + for (unsigned int i = 0; i < buffers.size() * 100; i++) {
> >> + int nBuffer = i % buffers.size();
> >> + int index = cache->get(*buffers[nBuffer].get());
> >> +
> >> + if (index != nBuffer) {
> >> + std::cout << "Expected index " << nBuffer
> >> + << " got " << index << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + cache->put(index);
> >> + }
> >> +
> >> + return TestPass;
> >> + }
> >> +
> >> + /*
> >> + * Test that randomly putting buffers to the cache always results in a
> >> + * valid index.
> >> + */
> >> + int testRandom(V4L2BufferCache *cache,
> >> + const std::vector<std::unique_ptr<FrameBuffer>> &buffers)
> >> + {
> >> + for (unsigned int i = 0; i < buffers.size() * 100; i++) {
> >> + int nBuffer = rand() % buffers.size();
> >
> > Is rand() a prng? Or does it get arbitrary random data?
>
> To be fully correct I think one need to seed rand() with srand().
>
> > It would be useful if this was based around a prng (which is perhaps
> > seeded randomly) so that we can ensure we can reliably repeat a failing
> > test....
> >
> > Then in any event of failure (and providing that the failure test case
> > prints it's random seed in the logs) we can hardcode the seed into the
> > binary and repeat the failing case to identify the root-cause.
> >
> > That's mostly a more general comment about seeing random usage in tests
> > than this specific use-case of course, but I fear it may still be
> > applicable in some aspect.
>
> I agree there could be tests where this level of reproducibility would
> be highly desirable. I'm not so concerned about this particular test
> case tho.
>
> If you feel strongly about it I'm not against it but then I think we
> shall provide a helper class that can be reused for all our testcases in
> case they need random numbers.
I agree with Kieran that tests should be reproducible. How about
std::mt19937 gen;
std::uniform_int_distribution<> dist(0, buffers.size() - 1);
...
int nBuffer = dist(gen);
This will be a PRNG and should always produce the same results. We can
specify a seed when constructing gen, otherwise the value 5489 is used.
> >> + int index = cache->get(*buffers[nBuffer].get());
> >> +
> >> + if (index < 0) {
> >> + std::cout << "Failed lookup from cache"
> >> + << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + cache->put(index);
> >> + }
> >> +
> >> + return TestPass;
> >> + }
> >> +
> >> + /*
> >> + * Test that using a buffer more frequently keeps it hot in the cache at
> >> + * all times.
> >> + */
> >> + int testHot(V4L2BufferCache *cache,
> >> + const std::vector<std::unique_ptr<FrameBuffer>> &buffers,
> >> + unsigned int hotFrequency)
> >> + {
> >> + /* Run the random test on the cache to make it messy. */
> >> + if (testRandom(cache, buffers) != TestPass)
> >> + return TestFail;
> >> +
> >> + /* Pick a hot buffer at random and store its index */
> >> + int hotBuffer = rand() % buffers.size();
> >> + int hotIndex = cache->get(*buffers[hotBuffer].get());
> >> + cache->put(hotIndex);
> >> +
> >> + /*
> >> + * Queue hot buffer at the requested frequency and make sure
> >> + * it stays hot.
> >> + */
> >> + for (unsigned int i = 0; i < buffers.size() * 100; i++) {
> >> + int nBuffer, index;
> >> + bool hotQueue = i % hotFrequency == 0;
> >> +
> >> + if (hotQueue)
> >> + nBuffer = hotBuffer;
> >> + else
> >> + nBuffer = rand() % buffers.size();
> >> +
> >> + index = cache->get(*buffers[nBuffer].get());
> >> +
> >> + if (index < 0) {
> >> + std::cout << "Failed lookup from cache"
> >> + << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + if (hotQueue && index != hotIndex) {
> >> + std::cout << "Hot buffer got cold"
> >> + << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + cache->put(index);
> >> + }
> >> +
> >> + return TestPass;
> >> + }
> >> +
> >> + int run() override
> >> + {
> >> + const unsigned int numBuffers = 8;
> >> +
> >> + StreamConfiguration cfg;
> >> + cfg.pixelFormat = V4L2_PIX_FMT_YUYV;
> >> + cfg.size = Size(600, 800);
> >> + cfg.bufferCount = numBuffers;
> >> +
> >> + BufferSource source;
> >> + int ret = source.allocate(cfg);
> >> + if (ret != TestPass)
> >> + return ret;
> >> +
> >> + if (source.buffers().size() != numBuffers) {
> >> + std::cout << "Got " << source.buffers().size()
> >> + << " buffers, expected " << numBuffers
> >> + << std::endl;
> >> + return TestFail;
> >> + }
> >> +
> >> + /*
> >> + * Test cache of same size as there are buffers, cache is
> >> + * created from a list of buffers and will be pre-populated.
> >> + */
> >> + V4L2BufferCache cacheFromBuffers(source.buffers());
> >> +
> >> + if (testSequential(&cacheFromBuffers, source.buffers()) != TestPass)
> >> + return TestFail;
> >> +
> >> + if (testRandom(&cacheFromBuffers, source.buffers()) != TestPass)
> >> + return TestFail;
> >> +
> >> + if (testHot(&cacheFromBuffers, source.buffers(), numBuffers - 1) != TestPass)
> >> + return TestFail;
> >> +
> >> + /*
> >> + * Test cache of same size as there are buffers, cache is not
> >> + * pre-populated.
> >> + */
> >> + V4L2BufferCache cacheFromNumbers(numBuffers);
> >> +
> >> + if (testSequential(&cacheFromNumbers, source.buffers()) != TestPass)
> >> + return TestFail;
> >> +
> >> + if (testRandom(&cacheFromNumbers, source.buffers()) != TestPass)
> >> + return TestFail;
> >> +
> >> + if (testHot(&cacheFromNumbers, source.buffers(), numBuffers - 1) != TestPass)
> >> + return TestFail;
> >> +
> >> + /*
> >> + * Test cache half the size of number of buffers used, cache is
> >> + * not pre-populated.
> >> + */
> >> + V4L2BufferCache cacheHalf(numBuffers / 2);
> >> +
> >> + if (testRandom(&cacheHalf, source.buffers()) != TestPass)
> >> + return TestFail;
> >> +
> >> + if (testHot(&cacheHalf, source.buffers(), numBuffers / 2 - 1) != TestPass)
> >> + return TestFail;
> >> +
> >> + return TestPass;
> >> + }
> >> +};
> >> +
> >> +} /* namespace */
> >> +
> >> +TEST_REGISTER(BufferCacheTest);
> >> diff --git a/test/v4l2_videodevice/meson.build b/test/v4l2_videodevice/meson.build
> >> index 5c52da7219c21cc3..685fcf6d16d72182 100644
> >> --- a/test/v4l2_videodevice/meson.build
> >> +++ b/test/v4l2_videodevice/meson.build
> >> @@ -5,6 +5,7 @@ v4l2_videodevice_tests = [
> >> [ 'controls', 'controls.cpp' ],
> >> [ 'formats', 'formats.cpp' ],
> >> [ 'request_buffers', 'request_buffers.cpp' ],
> >> + [ 'buffer_cache', 'buffer_cache.cpp' ],
> >> [ 'stream_on_off', 'stream_on_off.cpp' ],
> >> [ 'capture_async', 'capture_async.cpp' ],
> >> [ 'buffer_sharing', 'buffer_sharing.cpp' ],
--
Regards,
Laurent Pinchart
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