From e948ada380334b2bc697c51b45e0fd1856fd8a99 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Tue, 10 Mar 2026 13:01:04 +0100 Subject: [PATCH] software_isp: debayer_cpu: Add multi-threading support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add CPU soft ISP multi-threading support. Benchmark results for the Arduino Uno-Q with a weak CPU which is good for performance testing, all numbers with an IMX219 running at 3280x2464 -> 3272x2464: 1 thread : 147ms / frame, ~6.5 fps 2 threads: 80ms / frame, ~12.5 fps 3 threads: 65ms / frame, ~15 fps Adding a 4th thread does not improve performance. Tested-by: Barnabás Pőcze # ThinkPad X1 Yoga Gen 7 + ov2740 Reviewed-by: Milan Zamazal Signed-off-by: Hans de Goede Signed-off-by: Kieran Bingham --- Documentation/runtime_configuration.rst | 8 ++++ src/libcamera/software_isp/debayer_cpu.cpp | 47 ++++++++++++++++++++-- src/libcamera/software_isp/debayer_cpu.h | 10 +++++ 3 files changed, 62 insertions(+), 3 deletions(-) diff --git a/Documentation/runtime_configuration.rst b/Documentation/runtime_configuration.rst index e99ef2fb..651929a4 100644 --- a/Documentation/runtime_configuration.rst +++ b/Documentation/runtime_configuration.rst @@ -51,6 +51,7 @@ file structure: measure: skip: # non-negative integer, frames to skip initially number: # non-negative integer, frames to measure + threads: # integer >= 1, number of render threads to use, default 2 Configuration file example -------------------------- @@ -84,6 +85,7 @@ Configuration file example measure: skip: 50 number: 30 + threads: 2 List of variables and configuration options ------------------------------------------- @@ -167,6 +169,12 @@ software_isp.measure.skip, software_isp.measure.number Example `number` value: ``30`` +software_isp.threads + Number of render threads the software ISP uses when using the CPU. + This must be between 1 and 8 and the default is 2. + + Example value: ``2`` + Further details --------------- diff --git a/src/libcamera/software_isp/debayer_cpu.cpp b/src/libcamera/software_isp/debayer_cpu.cpp index fc3305d2..1de70b3b 100644 --- a/src/libcamera/software_isp/debayer_cpu.cpp +++ b/src/libcamera/software_isp/debayer_cpu.cpp @@ -76,6 +76,7 @@ DebayerCpuThread::DebayerCpuThread(DebayerCpu *debayer, unsigned int threadIndex debayer_(debayer), threadIndex_(threadIndex), enableInputMemcpy_(enableInputMemcpy) { + moveToThread(this); } /** @@ -107,11 +108,15 @@ DebayerCpu::DebayerCpu(std::unique_ptr stats, const GlobalConfigurat bool enableInputMemcpy = configuration.option({ "software_isp", "copy_input_buffer" }).value_or(true); - /* Just one thread object for now, which will be called inline rather than async */ - threads_.resize(1); + unsigned int threadCount = + configuration.option({ "software_isp", "threads" }).value_or(kDefaultThreads); + threadCount = std::clamp(threadCount, kMinThreads, kMaxThreads); + threads_.resize(threadCount); for (unsigned int i = 0; i < threads_.size(); i++) threads_[i] = std::make_unique(this, i, enableInputMemcpy); + + LOG(Debayer, Debug) << "Thread count " << threadCount; } DebayerCpu::~DebayerCpu() = default; @@ -746,6 +751,11 @@ void DebayerCpuThread::process(uint32_t frame, const uint8_t *src, uint8_t *dst) process2(frame, src, dst); else process4(frame, src, dst); + + debayer_->workPendingMutex_.lock(); + debayer_->workPending_ &= ~(1 << threadIndex_); + debayer_->workPendingMutex_.unlock(); + debayer_->workPendingCv_.notify_one(); } void DebayerCpuThread::process2(uint32_t frame, const uint8_t *src, uint8_t *dst) @@ -985,7 +995,21 @@ void DebayerCpu::process(uint32_t frame, FrameBuffer *input, FrameBuffer *output stats_->startFrame(frame); - threads_[0]->process(frame, in.planes()[0].data(), out.planes()[0].data()); + workPendingMutex_.lock(); + workPending_ = (1 << threads_.size()) - 1; + workPendingMutex_.unlock(); + + for (auto &thread : threads_) + thread->invokeMethod(&DebayerCpuThread::process, + ConnectionTypeQueued, frame, + in.planes()[0].data(), out.planes()[0].data()); + + { + MutexLocker locker(workPendingMutex_); + workPendingCv_.wait(locker, [&]() LIBCAMERA_TSA_REQUIRES(workPendingMutex_) { + return workPending_ == 0; + }); + } metadata.planes()[0].bytesused = out.planes()[0].size(); @@ -1004,6 +1028,23 @@ void DebayerCpu::process(uint32_t frame, FrameBuffer *input, FrameBuffer *output inputBufferReady.emit(input); } +int DebayerCpu::start() +{ + for (auto &thread : threads_) + thread->start(); + + return 0; +} + +void DebayerCpu::stop() +{ + for (auto &thread : threads_) + thread->exit(); + + for (auto &thread : threads_) + thread->wait(); +} + SizeRange DebayerCpu::sizes(PixelFormat inputFormat, const Size &inputSize) { Size patternSize = this->patternSize(inputFormat); diff --git a/src/libcamera/software_isp/debayer_cpu.h b/src/libcamera/software_isp/debayer_cpu.h index 8e57c273..9bd20820 100644 --- a/src/libcamera/software_isp/debayer_cpu.h +++ b/src/libcamera/software_isp/debayer_cpu.h @@ -15,6 +15,7 @@ #include #include +#include #include #include "libcamera/internal/bayer_format.h" @@ -41,6 +42,8 @@ public: std::tuple strideAndFrameSize(const PixelFormat &outputFormat, const Size &size); void process(uint32_t frame, FrameBuffer *input, FrameBuffer *output, const DebayerParams ¶ms); + int start(); + void stop(); SizeRange sizes(PixelFormat inputFormat, const Size &inputSize); const SharedFD &getStatsFD() { return stats_->getStatsFD(); } @@ -144,6 +147,13 @@ private: std::unique_ptr stats_; unsigned int xShift_; /* Offset of 0/1 applied to window_.x */ + static constexpr unsigned int kMinThreads = 1; + static constexpr unsigned int kMaxThreads = 8; + static constexpr unsigned int kDefaultThreads = 2; + + unsigned int workPending_ LIBCAMERA_TSA_GUARDED_BY(workPendingMutex_); + Mutex workPendingMutex_; + ConditionVariable workPendingCv_; std::vector> threads_; };