On: Vramfs: Vram Based Filesystem for Linux

[Dwedit]

Using something like this would keep the GPU powered on and unable to shut itself off.

[mjg59 → Dwedit]

Why? Vram has to be powered as long as you're scanning out of it, any competent design is going to support powering down most of the GPU while keeping RAM alive otherwise an idle desktop is going to suck way more power than necessary

[Dwedit → mjg59]

Some GPUs don't have scanout, such as Laptop GPUs that pipe pixels through the iGPU. Those fully power off when they're not in use.

[bobmcnamara → mjg59]

I wonder if any GPU is powering down chips or banks like you can on PC.

They all have MMUs right? So you could defrag all in-use memory to fewer refresh domains too.

[wtallis → bobmcnamara]

GPUs will drop memory clocks dynamically, with at least one supported clock speed that's intended to be just fast enough to support scanning out the framebuffer. I haven't seen any indication that anybody is dynamically offlining VRAM capacity.

[JackYoustra → bobmcnamara]

you can validate this yourself: if you have access to an A/H100, allocate a 30gb tensor and do nothing - you'll see nvidia-smi's reported wattage go up by a watt or so

[wtallis → JackYoustra]

That doesn't prove anything. Allocating a second 30GB chunk and seeing the power go up another Watt would be more convincing.