OpenCL Mesa (RustiCl) - MAX MEM ALLOC

Software darktable
1

Can someone please explain to me what MAX MEM ALLOC actually means?

[dt_opencl_device_init]
OpenCL Mesa platform `Mesa/X.org' --> `Radeon 8060S Graphics'
   DEVICE:                   0: 'Radeon 8060S Graphics (radeonsi, gfx1151, LLVM 21.1.6, DRM 3.64, 6.18.3-2-cachyos)'
   CONF KEY:                 cldevice_v5_rusticlradeon8060sgraphics
   PLATFORM, VENDOR & ID:    rusticl, Mesa:Mesa/X.org, ID=4098
   CANONICAL NAME:           rusticlradeon8060sgraphics
   DRIVER VERSION:           25.3.3-arch1.4
   DEVICE VERSION:           OpenCL 3.0 
   DEVICE_TYPE:              GPU, dedicated mem
   GLOBAL MEM SIZE:          16384 MB
   MAX MEM ALLOC:            1952 MB

My assumption was that it was the GPU memory “released” for Darktable. However, this does not seem to be the case.

Regardless of whether I set 4/8/16 GB for the iGPU in the BIOS, the value for Max Mem Alloc remains at around 2 GB.

My assumption seems to be incorrect, as the performance and thus the processing speed changes significantly.

As an example, there is no tiling in the benchmark with 16 GB and the run is around 50% faster than with 8 GB.

System used:
Hardware: ASUS ROG Flow Z13 (2025 model)
CPU/APU: AMD Ryzen AI MAX+ 395 w/ Radeon 8060S (32 threads)
RAM: 32 GB (Unified)
OS: Arch Linux (CachyOS), Kernel 6.18.2
Driver: AMD ROCm / OpenCL 2.0 (Driver Version 3581.0)
Darktable Version: 5.4.0

Chris

2

MAximum MEMory ALLOCation per allocation request. That means you have to ask multiple chunks of you need more

1 Like
3
1 Like
4

Just curious, are you the same person that opened [Ryzen AI Max+ 395 / gfx1151] Poor OpenCL performance on APU: Pinned Memory fails & CPU fallbacks · Issue #20071 · darktable-org/darktable · GitHub?

1 Like
5

The limit for allocating a buffer is no practical restriction. You have 4floats per pixel so 100mpixels will fit. 2gb is pretty common btw.

1 Like
6

Yes, I am. Thank you for the additional information on GitHub.

Thanks for the info. To understand it better, I calculated it myself and came up with approx. 135 MP for the 2 GB.

Thanks also to everyone else for your answers.

During my test, DT occasionally reset the settings.
cldevice_v5_rusticlradeon8060sgraphics=0 100 0 16 16 128 0 0 0.000 18017414545054485787384748179456.000 0.250

advantage hint seems to be getting a bit out of hand. However, this is purely cosmetic; resetting it to 0.000 does not produce a faster result.

Chris