All I know is certain i/o tasks in particular get at least equal treatment, if not top priority it seems like sometimes, and bring the UI to a screeching halt in certain scenarios. At first I thought the same, that if I simply adjusted the niceness level of, say, all X.org operations over that of other operations like compiling or copying or whatever, that it would resolve that problem.
Originally Posted by schmidtbag
However, Linus' comment that niceness levels are absolute, and you may want things to be more dynamic than that and fine-grained. For instance, if Xorg started being mean, you wouldn't want all your other processes to be destroyed. That's my understanding of that anyway.
Also, I think this issue is more complex than just scheduling of jobs, and there seems to have been a lot of improvements in actually making things more able to run in parallel, or in other words I think the multitasking ability of Linux just got a whole lot better with the recent coding that has gone into it. Being also able to make it so GUI responsiveness and user interaction in general gets higher priority is just one of the improvements.
Seriously, before all this, Linux had much worse multitasking capabilities than Windows 2000 did. Very happy to see this getting fixed.