py-videocore7

A Python library for GPGPU programming on Raspberry Pi 5, which realizes assembling and running QPU programs.

For Raspberry Pi Zero/1/2/3, use Idein/py-videocore instead.

For Raspberry Pi 4, use Idein/py-videocore6 instead.

About VideoCore VII QPU

Raspberry Pi 5 (BCM2712) has a GPU named VideoCore VII QPU in its SoC. The basic instruction set (add/mul ALU dual issue, three delay slots et al.) remains the same as VideoCore VI QPU of Raspberry Pi 4, and some units now perform differently.

• VideoCore IV QPU @ 250MHz: 250 [MHz] x 3 [slice] x 4 [qpu/slice] x 4 [physical core/qpu] x 2 [op/cycle] = 24 [Gflop/s]
• VideoCore IV QPU @ 300MHz: 300 [MHz] x 3 [slice] x 4 [qpu/slice] x 4 [physical core/qpu] x 2 [op/cycle] = 28.8 [Gflop/s]
• VideoCore VI QPU @ 500MHz: 500 [MHz] x 2 [slice] x 4 [qpu/slice] x 4 [physical core/qpu] x 2 [op/cycle] = 32 [Gflop/s]
• VideoCore VII QPU @ 800MHz: 800 [MHz] x 3 [slice] x 4 [qpu/slice] x 4 [physical core/qpu] x 2 [op/cycle] = 76.8 [Gflop/s]

Requirements

py-videocore7 communicates with the V3D hardware through /dev/dri/card0, which is exposed by the DRM V3D driver. To access the device, you need to belong to video group or be root user. If you choose the former, run sudo usermod --append --groups video $USER (re-login to take effect).

Installation

Install uv and clone py-videocore7 and run with uv:

$ sudo apt update
$ sudo apt upgrade
$ sudo apt install git
$ git clone https://github.com/Idein/py-videocore7.git
$ cd py-videocore7/
$ uv run example/sgemm.py

Running tests and examples

In the py-videocore7 directory cloned above:

$ uv run pytest -vs tests

$ uv run examples/sgemm.py
==== sgemm example (1024x1024 times 1024x1024) ====
numpy: 0.0390 sec, 55.1937 Gflop/s
QPU:   0.1006 sec, 21.3827 Gflop/s
Minimum absolute error: 0.0
Maximum absolute error: 0.0003814697265625
Minimum relative error: 0.0
Maximum relative error: 0.13134673237800598

$ uv run examples/scopy.py
==== CPU scopy example (24.0 Mi elements) ====
0.06235705600010988 sec, 1614.3048190059296 MB/s
==== QPU 1 thread scopy example (24.0 Mi elements) ====
Preparing for buffers...
Executing on QPU...
0.05958151100003306 sec, 1689.5055917588957 MB/s
==== QPU 12 threads scopy example (24.0 Mi elements) ====
Preparing for buffers...
Executing on QPU...
0.02430019499934133 sec, 4142.489227050586 MB/s

References

• DRM V3D driver which controls QPU via hardware V3D registers: linux/drivers/gpu/drm/v3d
• Mesa library which partially includes the QPU instruction set: mesa/src/broadcom/qpu
• py-videocore: Idein/py-videocore
• py-videocore6: Idein/py-videocore6