Two GPUs

[Werewolf]

Just trying an experiment with Lc0.

To use two graphics cards, should they be set to run in SLI or independently?

Thanks

[smatovic]

Just trying an experiment with Lc0.

To use two graphics cards, should they be set to run in SLI or independently?

Thanks

SLI has only effect for rendering graphics in video games,
so you do not need to set up SLI for Cuda or OpenCL.

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Srdja

[Javier Ros]

Just trying an experiment with Lc0.

To use two graphics cards, should they be set to run in SLI or independently?

Thanks

You must choose which GPU to use, or both, gpu=0 is for the first GPU and gpu=1 the second, for example in Cutechess

-engine name="Lc0201_32644" cmd="lc0.exe" option.Threads=4 nodes=8000 option.Backend=multiplexing option.BackendOptions="(backend=cudnn,gpu=0),(backend=cudnn,gpu=1)"

for use both GPU in Arena you must set:

Backend: Multiplexing
BackendOptions: (backend=cudnn,gpu=0),(backend=cudnn,gpu=1)

[Werewolf]

for use both GPU in Arena you must set:

Backend: Multiplexing
BackendOptions: (backend=cudnn,gpu=0),(backend=cudnn,gpu=1)

For the RTX cards presumably it'd look like this:

Backend: Multiplexing
BackendOptions: (backend=cudnn-fp16,gpu=0),(backend=cudnn-fp16,gpu=1)

[Javier Ros]

for use both GPU in Arena you must set:

Backend: Multiplexing
BackendOptions: (backend=cudnn,gpu=0),(backend=cudnn,gpu=1)

For the RTX cards presumably it'd look like this:

Backend: Multiplexing
BackendOptions: (backend=cudnn-fp16,gpu=0),(backend=cudnn-fp16,gpu=1)

Yes

[mclane]

for use both GPU in Arena you must set:

Backend: Multiplexing
BackendOptions: (backend=cudnn,gpu=0),(backend=cudnn,gpu=1)

For the RTX cards presumably it'd look like this:

Backend: Multiplexing
BackendOptions: (backend=cudnn-fp16,gpu=0),(backend=cudnn-fp16,gpu=1)

Yes

What is the difference in these two parameters ??
I do have an old pc with an old GTX 690.
It has 2 gpu cores.
I tried the first parameters and it looks like then both gpus are running 100 %.

[Javier Ros]

for use both GPU in Arena you must set:

Backend: Multiplexing
BackendOptions: (backend=cudnn,gpu=0),(backend=cudnn,gpu=1)

For the RTX cards presumably it'd look like this:

Backend: Multiplexing
BackendOptions: (backend=cudnn-fp16,gpu=0),(backend=cudnn-fp16,gpu=1)

Yes

What is the difference in these two parameters ??
I do have an old pc with an old GTX 690.
It has 2 gpu cores.
I tried the first parameters and it looks like then both gpus are running 100 %.

These parameters are for two physically different cards, on a motherboard that supports two PCIE slots.

[M ANSARI]

I am also thinking of setting up 2 GPU's for LC0. So is this code to be added to the .dll files? How do you get Leela to use both GPU's on CB GUI? Just install the UCI engine and add an edited .txt file?

How about if you do setup in SLI, will LC0 consider 2 x GPU's as one GPU if SLI or Crossfire is used?

[Javier Ros]

I am also thinking of setting up 2 GPU's for LC0. So is this code to be added to the .dll files? How do you get Leela to use both GPU's on CB GUI? Just install the UCI engine and add an edited .txt file?

How about if you do setup in SLI, will LC0 consider 2 x GPU's as one GPU if SLI or Crossfire is used?

I do not know the answer to the last question.

No SLI required, no txt file, in Chessbase you must only Create UCI Engine,
in Parameter, you must set Backend to Multiplexing and in BackendOptions you must write
(backend=cudnn,gpu=0),(backend=cudnn,gpu=1)

It is advisable to add to the name the version 32xxx and set Priority to Below Normal (recommended for all engines)

[smatovic]

How about if you do setup in SLI, will LC0 consider 2 x GPU's as one GPU if SLI or Crossfire is used?

SLI and Crossfire are only used for generating graphics, Cuda and OpenCL con not use these.

SLI was introduced with the Vodoo 2 3D-accelerator cards by 3dfx,
the technique splits the graphics workload across the gpus,
imagine that one gpu renders only the odd frames and one gpu renders only the even frames.

https://en.wikipedia.org/wiki/Scalable_Link_Interface

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Srdja