alt Hacker NewsIndeed it can be reallocated, needs a reboot though. I've gotten up to around 110 GB before running into OOM issues. I set it at 108 GB to provide a little headroom: https://www.jeffgeerling.com/blog/2025/increasing-vram-alloc...
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No need for a reboot, echo 9999 >/sys/module/ttm/parameters/pages_limit
You're talking about an allocator policy for when to allow GTT and when not, not the old firmware-level VRAM split thing where whatever size the BIOS sets for VRAM is permanently away from the CPU. The max GTT limit is there to decrease accidental footguns, it's not a technological limitation; at least earlier the default policy was to reserve 1/4 of RAM for non-GPU use, and 1/4*128 GB=32GB is more than enough so you're looking to adjust the policy. It's just an if statement in the kernel, GTT the mechanism doesn't limit it, and deallocating a chunk of memory used by the GPU returns it to the general kernel memory pool, where it can next be used by the CPU again.
Also, from your link:
> It seems like tools will have to adapt to dynamic VRAM allocation, as none of the monitoring tools I've tested assume VRAM can be increased on the fly.
amdgpu_top shows VRAM (the old fixed thing) and GTT (dynamic) separately.