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by 6by9
Fri Oct 09, 2020 10:58 am
Forum: General discussion
Topic: RAM speed
Replies: 39
Views: 3116

Re: RAM speed

... possible on the raspberry 4? If so how is that possible? Just names of what I should google is enough. "L1 cache" for which hardware block? VPU, QPU, TFU, HVS, or ARM? ARM caching is under the control of the Linux kernel - mess to your heart's content if you understand the ARM MMUs well enough. ...
by cleverca22
Thu Oct 08, 2020 12:25 am
Forum: General discussion
Topic: Any idea, how to combine GPU power of two pi 4's?
Replies: 16
Views: 782

Re: Any idea, how to combine GPU power of two pi 4's?

the major difference, is that the QPU is float based, while VPU is int only I have never tried it but most reverse engineering efforts describe the VPU as supporting floating point - https://github.com/hermanhermitage/videocoreiv/wiki/VideoCore-IV-Programmers-Manual ...
by 6by9
Wed Oct 07, 2020 4:47 pm
Forum: General discussion
Topic: Any idea, how to combine GPU power of two pi 4's?
Replies: 16
Views: 782

Re: Any idea, how to combine GPU power of two pi 4's?

... the ThreadX operating system within the GPU, is responsible for marshalling everything else, handling mailbox calls, running threads, setting QPU's and everything else in motion. The other VPU I believe is unused and available for executing user code. Both are running ThreadX, with threads/tasks ...
by hippy
Wed Oct 07, 2020 11:18 am
Forum: General discussion
Topic: Any idea, how to combine GPU power of two pi 4's?
Replies: 16
Views: 782

Re: Any idea, how to combine GPU power of two pi 4's?

... the ThreadX operating system within the GPU, is responsible for marshalling everything else, handling mailbox calls, running threads, setting QPU's and everything else in motion. The other VPU I believe is unused and available for executing user code. The two VPU cores are fairly traditional ...
by cleverca22
Wed Oct 07, 2020 1:12 am
Forum: General discussion
Topic: Any idea, how to combine GPU power of two pi 4's?
Replies: 16
Views: 782

Re: Any idea, how to combine GPU power of two pi 4's?

Thanks for correcting me, yes QPU not VPU. All are on the GPU. After the VPU boots the ARM cores what are the VPU's doing? They do more with start_x loaded. Monitoring temperature? Is that only one VPU? What is the second VPU doing? with ...
by Gavinmc42
Wed Oct 07, 2020 12:32 am
Forum: General discussion
Topic: Any idea, how to combine GPU power of two pi 4's?
Replies: 16
Views: 782

Re: Any idea, how to combine GPU power of two pi 4's?

Thanks for correcting me, yes QPU not VPU.
All are on the GPU.

After the VPU boots the ARM cores what are the VPU's doing?
They do more with start_x loaded.
Monitoring temperature?
Is that only one VPU?
What is the second VPU doing?
Without accelerated video output are the QPU's used for anything?
by cleverca22
Tue Oct 06, 2020 11:00 pm
Forum: General discussion
Topic: Any idea, how to combine GPU power of two pi 4's?
Replies: 16
Views: 782

Re: Any idea, how to combine GPU power of two pi 4's?

Gavinmc42 wrote:
Tue Oct 06, 2020 5:01 am
https://github.com/Idein/py-videocore6
For maths type stuff on the VPU.
that repo is for using the QPU cores on the V3D, not the VPU cores

the major difference, is that the QPU is float based, while VPU is int only, and the QPU can do more computations per clock
by cleverca22
Sun Sep 27, 2020 6:03 pm
Forum: General discussion
Topic: Q: How much would a Raspberry pi 4 costed with two CPUs
Replies: 38
Views: 1252

Re: Q: How much would a Raspberry pi 4 costed with two CPUs

... complication of how many cores the pi even has, its a lot higher then you think there is 1-4 arm cores (based on model) 2 vpu cores there are ~192 qpu cores (less on pi4, but higher clock), that run opengl shaders there are the ISP and VCE cores (basically a black-box), that handle camera image ...
by cleverca22
Sun Sep 06, 2020 11:51 pm
Forum: Bare metal, Assembly language
Topic: Raspberry Pi 4 Framebuffer & USB
Replies: 3
Views: 347

Re: Raspberry Pi 4 Framebuffer & USB

... I just scanned it a few seconds, so not sure is that is what you need, but it look great to me. that document only covers the QPU and V3D components, which run shaders and power opengl the VPU where the main firmware runs is entirely missing from that doc you can basically ...
by graysky
Mon Jul 20, 2020 6:22 pm
Forum: Graphics, sound and multimedia
Topic: how to compile ffmpeg with hardware acceleration support
Replies: 12
Views: 1817

Re: how to compile ffmpeg with hardware acceleration support

Thank you both! This was the guidance I needed. All sorted and up and running now. I am getting very similar errors building the popcornmix/gbm kodi branch. Wondering if you could elaborate a bit on what you did to fix it? ... AR libavutil/libavutil.a AR libavformat/libavformat.a AR libavcodec/liba...
by jamesh
Wed Jul 15, 2020 1:12 pm
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 22
Views: 1733

Re: gpu_fft for RPi4?

ah, i only heard about the reduced number of QPU's running at a higher clock, giving the same effective performance didnt know about all of the other changes Not just the clock change - IIRC, the reduced die area because of fewer QPU's means more ...
by crossbar
Wed Jul 15, 2020 12:55 pm
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 22
Views: 1733

Re: gpu_fft for RPi4?

The instruction set and architecture of VC6 QPU have changed from VC4 QPU The RegisterFiles (RF) A and B are now more symmetric, a new 16 bit data type is introduced and ... Though there must exist an internal document of VC6 QPU, it is not publicly ...
by hjimbens
Mon Jul 13, 2020 11:40 am
Forum: OpenGLES
Topic: Best practice in shaders....
Replies: 3
Views: 615

Re: Best practice in shaders....

... be slower. If you are using the fkms or kms open source driver you can inspect the generated code by starting you software with export V3D_DEBUG=qpu For a typical fragment shader in my code this generates the following output: MESA_SHADER_FRAGMENT prog 9/1 QPU: 0x3dd014c6bbfc0000 nop ; mov rf19, ...
by Akane
Sun Jul 12, 2020 12:44 pm
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 22
Views: 1733

Re: gpu_fft for RPi4?

Though there must exist an internal document of VC6 QPU, it is not publicly available (c.f. a post by jamesh ). However, you can refer to the open-source Mesa library , which generates QPU instructions from its internal IR, for the information of the ...
by cleverca22
Sun Jul 12, 2020 12:19 pm
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 22
Views: 1733

Re: gpu_fft for RPi4?

... use our C libraries listed in https://gist.github.com/Terminus-IMRC/c5d1f6f78c890c26947a4553296b50d6 . The instruction set and architecture of VC6 QPU have changed from VC4 QPU e.g. the number of QPUs has been decreased, VPM/DMA is no longer available, and TMU can now write to memory in addition ...
by Akane
Sun Jul 12, 2020 12:17 pm
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 22
Views: 1733

Re: gpu_fft for RPi4?

... use our C libraries listed in https://gist.github.com/Terminus-IMRC/c5d1f6f78c890c26947a4553296b50d6 . The instruction set and architecture of VC6 QPU have changed from VC4 QPU e.g. the number of QPUs has been decreased, VPM/DMA is no longer available, and TMU can now write to memory in addition ...
by cleverca22
Sun Jul 12, 2020 3:34 am
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 22
Views: 1733

Re: gpu_fft for RPi4?

It seems that the EXECUTE_QPU Mailbox call is no longer usable on Pi4 (system freezes when you use it). However, py-videocore6 already has the functionalities to allocate/free memory and post a QPU job via the V3D DRM kernel driver. The ...
by Akane
Sun Jul 12, 2020 3:03 am
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 22
Views: 1733

Re: gpu_fft for RPi4?

It seems that the EXECUTE_QPU Mailbox call is no longer usable on Pi4 (system freezes when you use it). However, py-videocore6 already has the functionalities to allocate/free memory and post a QPU job via the V3D DRM kernel driver. The ...
by cleverca22
Thu Jul 09, 2020 3:13 am
Forum: General programming discussion
Topic: gpu_fft for RPi4?
Replies: 22
Views: 1733

Re: gpu_fft for RPi4?

... it looks like hello_fft is based around an undocumented mailbox property, to execute QPU programs (its is immediately after VPU program execution) i think the root problem, is that the rpi4 start4.elf firmware lacks the opengl stack, ...
by hippy
Fri Jul 03, 2020 12:17 pm
Forum: Bare metal, Assembly language
Topic: "Execute Code" (and other) mailbox tags?
Replies: 10
Views: 843

Re: "Execute Code" (and other) mailbox tags?

... Pi 3's four ARM cores? Yes. The VPU ISA is very similar to ARM but with fewer instructions. Yes, but Pi 3 has another processor named VideoCore IV QPU in addition to ARM and VPU, which means that three processors run in parallel! Actually all Pi's. The Pi VideoCores have two VPU's, vector (scalar) ...
by Akane
Fri Jul 03, 2020 10:07 am
Forum: Bare metal, Assembly language
Topic: "Execute Code" (and other) mailbox tags?
Replies: 10
Views: 843

Re: "Execute Code" (and other) mailbox tags?

Yes, but Pi 3 has another processor named VideoCore IV QPU in addition to ARM and VPU, which means that three processors run in parallel!
by ejolson
Thu Jul 02, 2020 3:00 pm
Forum: General discussion
Topic: Any benifit to overclocking gpu_freq for purely headless users?
Replies: 11
Views: 829

Re: Any benifit to overclocking gpu_freq for purely headless users?

I learned so many things from Raspberry Pi and QPU that I could never know, and with the experience, I got a stimulating part-time job that altered my whole life though I'm still a student. So I think it's not bad to learn QPU :D Problem is that ...
by jamesh
Thu Jul 02, 2020 2:39 pm
Forum: General discussion
Topic: Any benifit to overclocking gpu_freq for purely headless users?
Replies: 11
Views: 829

Re: Any benifit to overclocking gpu_freq for purely headless users?

I learned so many things from Raspberry Pi and QPU that I could never know, and with the experience, I got a stimulating part-time job that altered my whole life though I'm still a student. So I think it's not bad to learn QPU :D Problem is that ...
by Akane
Thu Jul 02, 2020 1:02 pm
Forum: General discussion
Topic: Any benifit to overclocking gpu_freq for purely headless users?
Replies: 11
Views: 829

Re: Any benifit to overclocking gpu_freq for purely headless users?

I learned so many things from Raspberry Pi and QPU that I could never know, and with the experience, I got a stimulating part-time job that altered my whole life though I'm still a student. So I think it's not bad to learn QPU :D
by jamesh
Thu Jul 02, 2020 10:03 am
Forum: General discussion
Topic: Any benifit to overclocking gpu_freq for purely headless users?
Replies: 11
Views: 829

Re: Any benifit to overclocking gpu_freq for purely headless users?

... The exact answer depends on the details. Not every headless PI does without the GPU. Example: If your headless Pi use the vector-processing-QPUs in the videocore there are benefits in increasing gpu-freq. Not linear - because crossing clock domain boundaries does (sometimes) introduce stalls. ...

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