Title: Mounting video ram on Linux
Author: Solène
Date: 10 February 2024
Tags: linux
Description: In this article, you will learn how to store data in your
GPU memory on Linux

Introduction

Hi, did you ever wonder if you could use your GPU memory as a mount
point, like one does with tmpfs and RAM?

Well, there is a project named vramfs that allows you to do exactly
this on FUSE compatible operating system.

In this test, I used an NVIDIA GTX 1060 6GB in an external GPU case
connected with a thunderbolt cable to a Lenovo T470 laptop running
Gentoo.

ramfs official GitHub project page
<https://github.com/Overv/vramfs>

Setup

Install the dependencies, you need a C++ compiler and OpenCL headers
for C++ (the package name usually contains "clhpp").

Download the sources, either with git or using an archive.

Run `make` and you should obtain a binary in `bin/vramfs`.

Usage

It's pretty straightforward to use, as root, run `vramfs /mountpoint
3G` to mount a 3 GB storage on `/mountpoint`.

The program will stay in foreground, use Ctrl+C to unmount and stop the
mount point.

Speed test

I've been doing a simple speed test using `dd` to measure the write
speed compare to a tmpfs.

The vramfs mount point was able to achieve 971 MB/s, it was CPU bound
by the FUSE program because FUSE isn't very efficient compared to a
kernel module handling a file system.

Meanwhile, the good old tmpfs reached 3.2 GB/s without using much CPU,
this is a clear winner.

Limitations

I tried to use the vram mount point as a temporary directory for
portage (the Gentoo tool building packages), but it didn't work due to
an error. After this error, I had to umount and recreate the mount
point otherwise I was left with an irremovable directory. There are
bugs in vramfs, no doubts here :-)

Arch Linux wiki has a guide explaining how to use vramfs to store a
swap file, but it seems to be risky for the system stability.

ArchWiki: Swap on video
<https://wiki.archlinux.org/title/Swa...USE_filesystem>

Conclusion

It's pretty cool to know that on Linux you can do almost what you want,
even store data in your GPU memory.

However, I'm still trying to figure a real use case for vramfs except
that it's pretty cool and impressive. If you figure a useful
situation, please let me know.

From:
<gopher://dataswamp.org/1/~solene/art...-vram-on-linux>

Reminds me of VGADISK.SYS
<ftp://ftp.oldskool.org/pub/simtelnet...sk/vgadisk.zip>

Have you figured out a use case? I am very curious why in the world you'd want to do this? But it sounds interesting enough for me to want to ask you that!

Now if you could just mount the GOU's firmware....