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

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Message-ID: <462A144B.9000400@tmr.com>
Date:	Sat, 21 Apr 2007 09:40:27 -0400
From:	Bill Davidsen <davidsen@....com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Matt Mackall <mpm@...enic.com>, Nick Piggin <npiggin@...e.de>,
	William Lee Irwin III <wli@...omorphy.com>,
	Peter Williams <pwil3058@...pond.net.au>,
	Mike Galbraith <efault@....de>,
	Con Kolivas <kernel@...ivas.org>, Ingo Molnar <mingo@...e.hu>,
	ck list <ck@....kolivas.org>,
	Bill Huey <billh@...ppy.monkey.org>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [Announce] [patch] Modular Scheduler Core and Completely Fair
   Scheduler [CFS]

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@....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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