Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS]

Linus Torvalds
2007-04-18T14:49:33Z

On Wed, 18 Apr 2007, Matt Mackall wrote:
>
> Why is X special? Because it does work on behalf of other processes?
> Lots of things do this. Perhaps a scheduler should focus entirely on
> the implicit and directed wakeup matrix and optimizing that
> instead[1].

I 100% agree - the perfect scheduler would indeed take into account where
the wakeups come from, and try to "weigh" processes that help other
processes make progress more. That would naturally give server processes
more CPU power, because they help others

I don't believe for a second that "fairness" means "give everybody the
same amount of CPU". That's a totally illogical measure of fairness. All
processes are _not_ created equal.

That said, even trying to do "fairness by effective user ID" would
probably already do a lot. In a desktop environment, X would get as much
CPU time as the user processes, simply because it's in a different
protection domain (and that's really what "effective user ID" means: it's
not about "users", it's really about "protection domains").

And "fairness by euid" is probably a hell of a lot easier to do than
trying to figure out the wakeup matrix.

Linus