Choice of GPU for VASP 6
Posted: Wed Apr 07, 2021 11:13 pm
At my department, we are currently trying to build a small GPU cluster that will fill the needs of the different groups that do computations. The choice so far has landed on NVIDIA Titan RTX with 24 GB GDDR6 RAM. I am trying to check if it will work with VASP 6 (we recently bought the license but have not installed it anywhere yet -- I'm still using 5.4.4 for "normal/non-GPU" computations). Is this card compatible with the VASP OpenACC port requirements? I see some conflicting data around the web and don't understand all the different coding libraries and standards that are in use in the world of GPUs. Here's a quick summary of the card: https://www.techpowerup.com/gpu-specs/titan-rtx.c3311.
For example, I don't understand how VASP can require CUDA 10 -compatible libraries when even the most current NVIDIA architecture (Ampere, at least the one for consumer cards like RTX 3000 series) use CUDA 8, unless they support everything from CUDA 8 and upwards. The Titan RTX is of Turing architecture, which seems to be the consumer architecture of the same generation as Volta, so from 2018-2019, and uses CUDA 7.5. Also, I cannot find any info about OpenACC. Like, what versions are supported by what cards, or if they all support all versions. In an NVIDIA article (https://developer.nvidia.com/blog/nvidi ... rformance/) they say "Scientists can run VASP 6 on any NVIDIA GPU". Is it that simple?
The recommendation at https://www.vasp.at/wiki/index.php/Open ... rt_of_VASP list only "professional/Datacenter" cards, but at our department the group that does AI chose the hardware, since they are the ones that actually know all this stuff about hardware, and I guess the choice was to buy several "normal" graphics cards per workstation rather than one really expensive one like the V100. Will two 24 GB Titan cards per workstation have enough RAM for models that use about 64 GB on non-GPU VASP? These workstations will also have at least 128 GB normal RAM -- does GPU-ported VASP use video RAM in conjunction with normal RAM to off-load the demands on the graphics memory? Does the normal CPU have any impact? Again, I have no clue about how GPU computations work or what kind of demands they put on the system as a whole.
Hope someone can clarify this.
For example, I don't understand how VASP can require CUDA 10 -compatible libraries when even the most current NVIDIA architecture (Ampere, at least the one for consumer cards like RTX 3000 series) use CUDA 8, unless they support everything from CUDA 8 and upwards. The Titan RTX is of Turing architecture, which seems to be the consumer architecture of the same generation as Volta, so from 2018-2019, and uses CUDA 7.5. Also, I cannot find any info about OpenACC. Like, what versions are supported by what cards, or if they all support all versions. In an NVIDIA article (https://developer.nvidia.com/blog/nvidi ... rformance/) they say "Scientists can run VASP 6 on any NVIDIA GPU". Is it that simple?
The recommendation at https://www.vasp.at/wiki/index.php/Open ... rt_of_VASP list only "professional/Datacenter" cards, but at our department the group that does AI chose the hardware, since they are the ones that actually know all this stuff about hardware, and I guess the choice was to buy several "normal" graphics cards per workstation rather than one really expensive one like the V100. Will two 24 GB Titan cards per workstation have enough RAM for models that use about 64 GB on non-GPU VASP? These workstations will also have at least 128 GB normal RAM -- does GPU-ported VASP use video RAM in conjunction with normal RAM to off-load the demands on the graphics memory? Does the normal CPU have any impact? Again, I have no clue about how GPU computations work or what kind of demands they put on the system as a whole.
Hope someone can clarify this.