I like to follow articles benchmarking OSs on phoronix a lot. Whenever Arch looks bad I see comments riddled with saying that is because the default scheduler sucks. I feel fairly compitent with Linux but for some reason schedulers seemed like this black box that lives in the realm of places where I normally break my OS from not paying close attention.

Is it a program run by something like systemd? Is it a config or patch of the kernel? Which ones are good and how important are they?

Anyways, any advice on schedulers would be appreciated.