linux-kernel - Re: [sched-devel, patch-rfc] rework of "prioritize non-migratabletasks over migratable ones"

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Message-ID: <20080618103919.GH15255@elte.hu>
Date:	Wed, 18 Jun 2008 12:39:19 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Gregory Haskins <ghaskins@...ell.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Dmitry Adamushko <dmitry.adamushko@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [sched-devel, patch-rfc] rework of "prioritize
	non-migratabletasks over migratable ones"


* Gregory Haskins <ghaskins@...ell.com> wrote:

> >>> On Mon, Jun 16, 2008 at  3:17 PM, in message
> <1213643862.16944.142.camel@...ns>, Peter Zijlstra <a.p.zijlstra@...llo.nl>
> wrote: 
> > On Mon, 2008-06-16 at 19:59 +0200, Dmitry Adamushko wrote:
> > 
> >> One way or another, we have different aritifacts (and mine have likely
> >> more) but conceptually, both "violates" POSIX if a strict round-robin
> >> scheduling is required.
> > 
> > http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_08.html#t
> > ag_02_08_04_01
> > 
> > Is quite strict on what FIFO should do, and I know of two points where
> > we deviate and should work to match.
> 
> Thanks for the link, Peter.  When you read that, its pretty clear that 
> this whole concept violates the standard.  Its probably best to just 
> revert the patch and be done with it.

no, there's no spec violation here - the spec is silent on SMP issues.

the spec should not be read to force a global runqueue for RT tasks. 
That would be silly beyond imagination.

so ... lets apply Dmitry's nice simplification, hm?

	Ingo
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