Use or compile a kernel with BFQ and that kind of stuff takes care of itself without manually having to prioritize I/O. I don't get why BFQ hasn't been mainlined yet, it has the most sane I/O behavior for desktop use and stops all the issues you can have on linux of the desktop slowing to a crawl or music stuttering because you're compressing a 40gb folder or copying files.

Here's the page on the BFQ I/O scheduler: http://algo.ing.unimo.it/people/paolo/disk_sched/

Here's a list of precompiled kernels that have been patched with BFQ (and often some more desktop-use tuning): https://liquorix.net/#install for ubuntu and debian

https://www.archlinux.org/packages/extra/x86_64/linux-zen/ for archlinux

http://download.opensuse.org/repositories/home:/tiwai:/bfq/ for opensuse, BFQ as a kernel module

If you're wary of installing things outside of official repositories or compiling your own kernel, then archlinux is the only distro with a kernel option that has BFQ.