From: Con Kolivas <kernel@kolivas.org>
To: Maciej Soltysiak <solt2@dns.toxicfilms.tv>
Subject: Re: 2.6.15-rc5-mm2 :-)
Date: Tue, 13 Dec 2005 23:16:11 +1100
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On Tuesday 13 December 2005 22:13, Maciej Soltysiak wrote:
> Hello Con,
>
> Tuesday, December 13, 2005, 6:52:09 AM, you wrote:
> > I missed this announcement (been on leave for a while). This SCHED_BATCH
> > implementation is by Ingo and it it is not "idle" scheduling as I have
> > implemented in the staircase scheduler. This is just to restrict a task
> > to not having any interactive bonus at any stage and to have predictable
> > scheduling behaviour I guess.
>
> Thanks a lot. That's good anyway.
>
> If I understand correctly, if Ingo's version gets merged with linus' tree
> your implementions of SCHED_BATCH in -ck will be replacing the one from
> Ingo.

Yes. SCHED_BATCH in Ingo's implementation is more like turning off the=20
interactive setting in staircase, and the idle scheduling staircase offers =
is=20
extremely useful.

> A silly question. Is SCHED_BATCH-kind-of-thing a standard in Unices or
> general operating system engineering know-how? Or is this concept only
> available for Linux?

=46airly standard in Unices but prone to all sorts of priority inversion=20
starvation scenarios so very few implement it. In freebsd for example you c=
an=20
use their idle scheduling only if you are root to prevent this starvation -=
=20
which kind of makes it useless in practice. My implementation is fairly=20
robust at avoiding the priority inversion problem - at least I haven't seen=
 a=20
bug report about it for years since I address it :)

Cheers,
Con

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