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

[Bill Davidsen <davidsen@tmr.com>]

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
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