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

Bill Davidsen
2007-04-21T13:41:24Z

Linus Torvalds wrote:
>
> 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.
>
You probably want to consider the controlling terminal as well... do
you want to have people starting 'at' jobs competing on equal footing
with people typing at a terminal? I'm not offering an answer, just
raising the question.

And for some database applications, everyone in a group may connect with
the same login-id, then do sub authorization to the database
application. euid may be an issue there as well.

--
Bill Davidsen <davidsen@tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot