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Is anyone knowledgeable on VM performance issues?

For some reason, my VMs have been stuttering a lot, lately. I could play a game, have perfect 60 FPS, and then for no reason it'll drop to 20 FPS for a second or so. Opening image files in Windows' Photo application has like a 30% chance of completely freezing the whole system for a solid 5-10 seconds...

@cirno Sounds like potential harddisk errors with the physical portion the virtual disk is on. Is that possible?

@brandon I... don't know? The VM is running off an SSD, same one as the main operating system actually, and I have no performance issues on the host OS. Also new VMs with different virtual disks have the same performance issue.

@cirno Ahh then it's an IO bandwidth issue then, I would say.

I know that when I would do immense file transfers from an external drive to an internal one on my Linux install, it would slow down the OS until the transfer was finished, especially if I didn't renice the process.

The VMs likely run at less priority compared to the host OS, so if that's doing anything disk-heavy in the background, that will very likely affect the VM's performance

@brandon Is there any way to prevent the host from doing disk-heavy things, then? I could move the vhd to a hard drive, but running an OS off a hard drive is going to be painfully slow as well...

@cirno I would first look at the things using your disk constantly. Torrents, any automatic updates, backups, downloads, etc

@brandon Hmm, I often turn everything off before starting a VM, precisely to avoid performance bottlenecks. I sometimes just turn on the VM right after logging in.

Plus, the VM is a single-GPU passthrough thing, so the host's graphical environment gets turned off along with most applications, anyway.

@cirno Then I'm stumped, I hope you're able to find the cause

@brandon I just cloned the VM in questioned, putting the disk file on my HDD instead of my SSD. Literally no programs run off my HDD, it's only used for storage, so no IO priority shenanigans should occur...

...and yet the problem was still persisting.

@brandon Well, I've determined that it's not some I/O throughput or priority issue, but a system issue. Because when I make an identical VM but running Artix Linux instead of Windows 10, no such issues appear, everything is wonderfully smooth.

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