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Date: Wed, 25 Apr 2007 11:44:03 +0200
From: Ingo Molnar <mingo@elte.hu>
To: "Li, Tong N" <tong.n.li@intel.com>
Cc: William Lee Irwin III <wli@holomorphy.com>,
       Jeremy Fitzhardinge <jeremy@goop.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Nick Piggin <npiggin@suse.de>, Juliusz Chroboczek <jch@pps.jussieu.fr>,
       Con Kolivas <kernel@kolivas.org>, ck list <ck@vds.kolivas.org>,
       Bill Davidsen <davidsen@tmr.com>, Willy Tarreau <w@1wt.eu>,
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       Peter Williams <pwil3058@bigpond.net.au>,
       Thomas Gleixner <tglx@linutronix.de>, caglar@pardus.org.tr,
       Gene Heskett <gene.heskett@gmail.com>
Subject: Re: [REPORT] cfs-v4 vs sd-0.44
Message-ID: <20070425094403.GA3290@elte.hu>
References: <20070424212717.GR31925@holomorphy.com> <5FD5754DDBA0B1499B5A0B4BB5419485F72D3C@fmsmsx411.amr.corp.intel.com>
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* Li, Tong N <tong.n.li@intel.com> wrote:

> [...] A corollary of this is that if both threads i and j are 
> continuously runnable with fixed weights in the time interval, then 
> the ratio of their CPU time should be equal to the ratio of their 
> weights. This definition is pretty restrictive since it requires the 
> properties to hold for any thread in any interval, which is not 
> feasible. [...]

yes, it's a pretty strong definition, but also note that while it is 
definitely not easy to implement, the solution is nevertheless feasible 
in my opinion and there exists a scheduler that implements it: CFS.

	Ingo