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    SubjectRe: [sched-devel, patch-rfc] rework of "prioritize non-migratabletasks over migratable ones"
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    On Wed, 2008-06-18 at 12:39 +0200, Ingo Molnar wrote:
    > * Gregory Haskins <ghaskins@novell.com> wrote:
    >
    > > >>> On Mon, Jun 16, 2008 at 3:17 PM, in message
    > > <1213643862.16944.142.camel@twins>, Peter Zijlstra <a.p.zijlstra@chello.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.

    Sadly, some people do read it like that.

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

    As long as it doesn't wreck the per RQ queue model and only affects the
    SMP interaction that would be acceptable I guess.



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