Take Advantage Of 2GB and 4GB RAM for a Virtual Disk to extract Roms to

LiveFreeDead

I was reading up on how ROMS can and mostly are stored as a .zip or .7z and when you run them it will extract them to the zipped roms current path to execute them, I also know that this would often be kept on a Micro SD Card, the problem I see is SD cards wear out quickly with constant writing to them, so I was hoping that the main dev team of RetroPie would consider making an option available for a Virtual Disk Temp path(s) to reduce writes to the SD card by making the virtual disk the default extraction point for compressed roms. This would have a added benefit of loading roms faster as a virtual disk is MUCH faster than SD Read speeds. I was hearing how the 2GB and 4GB are overkill for most of the Emulation, this would add a feature to make use of such memory.

Sorry and disregard this if it is already possible within the RetroPie Settings , the Pi 4 4GB is my first Pi I have seen/used and I am keen to setup RetroPie for the first time in the near future. If I spot anymore improvements once I begin testing/building, I'll share them here.

Clyde

RetroArch extracts the roms to its cache directory (/tmp/retroarch by default). You can mount /tmp/retroarch to ram by adding this line to your /etc/fstab.

tmpfs	/tmp/retroarch	tmpfs	nosuid	0	0

Editing the fstab requires administrative permissions. One way to edit it is the command sudo nano /etc/fstab in the RetroPie console.

edit: The mount will take effect at the next boot or immediately by the command sudo mount -a.

edit 2: You should make a backup of your fstab before editing it, lest you make your system unbootable by mistake: sudo cp /etc/fstab /etc/fstab.backup

mitu

@LiveFreeDead that's something to have in mind. Besides what @Clyde said, there are a few instances where temporary archives are unpacked in /tmp/retropie-archive when a source installation is performed.
Maybe the whole /tmp can be RAM-backed - when enough memory is present.

Clyde

@mitu Yes, I also thought about that, but I didn't know how much of /tmp is used by RetroPie, so I played safe. At the moment, the /tmp of my Retropie only holds 44K after running a mame 2003 plus game and an SNES game for a short time for testing, so I think it should be okay.

@LiveFreeDead Just change /tmp/retroarch to just /tmp to mount it into ram completely. You can check its total size with the command sudo du -sh /tmp, and your system's free memory with free -h.

(The sudo before du is needed because /tmp holds at least one directory owned by root.)

Darksavior

@Clyde I tried /tmp/retroarch and it did not improve the loading times and I get this message after loading a game: rm: cannot remove /tmp/retroarch : Operation not permitted. I changed it to just /tmp and the message is gone but it still doesn't improve load times.

I'm using raspbian lite buster and retropie's pi4 repo. I guess this saves sd writes so that's a plus.

Clyde

@Darksavior Ah, so RA creates the directory on runtime and deletes it afterwards. Then it would be better to put the whole /tmp into ram.

That said, did the message prevent anything from happening? If not, one might just ignore it.

edit: As for the speed, @LiveFreeDead seemed more interested in preserving the flash memory of the sd card than to speed up the loading times.

LiveFreeDead

@Clyde The only issue I could foresee is a lack of space for DVD sized roms or dual PSX roms, these will still need to use a swapdisk or disk tmp folder on the SD card, that would be the only reason I could see it failing, if anyone can come up with a check that can revert to default tmp the feature would near be possible already :D thanks for running tests tho, good to know it doesn't increase speeds, I really thought it would have on n64 or dreamcast sized roms.

Clyde

@LiveFreeDead Alternatively, you could change RA's cache path to /dev/shm (shm = shared memory), the pre-installed ramdisk of Retropie. See https://github.com/RetroPie/RetroPie-Setup/wiki/RetroArch for the option cache_directory.

That way, you could use the ramdisk only for some systems, but not others.

Darksavior

@Clyde No problems loading games with that error message. I changed it to /tmp/ now, though.
@LiveFreeDead Well, you can disable runcommand's launch menu to shave off a few seconds :D

Clyde

@Darksavior One other potential problem with /tmp/retroarch came to my mind. If it doesn't exist on boot time because RA deleted it, the auto-mount via fstab will fail. After one successful mount however, it will be protected from deletion by the mount.

Thus, the safe sequence would be:

Create the directory via mkdir -p /tmp/retroarch
Edit the fstab like described above.
Reboot.

Then, the directory will be there on boot time, the mount to ram will happen, and prevent deletion until shutdown. Rinse and repeat. :)

This isn't necessary if the whole /tmp is mounted to ram, of course.