Date: Tue, 28 Jan 2003 11:29:14 -0500 (EST) From: Robert Watson <rwatson@FreeBSD.ORG> To: Julian Elischer <julian@elischer.org> Cc: Jeff Roberson <jroberson@chesapeake.net>, Matthew Dillon <dillon@apollo.backplane.com>, Steve Kargl <sgk@troutmask.apl.washington.edu>, Gary Jennejohn <garyj@jennejohn.org>, arch@FreeBSD.ORG Subject: Re: New scheduler - Interactivity fixes Message-ID: <Pine.NEB.3.96L.1030128111454.87213G-100000@fledge.watson.org> In-Reply-To: <Pine.BSF.4.21.0301252309090.89171-100000@InterJet.elischer.org>
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On Sat, 25 Jan 2003, Julian Elischer wrote:
> The standard proceedure for adding a new "to be standard" feature is:
>
> Make the new feature an option, leaving the original as default. Make
> the old one as a feature as well. Change the default
I know there are other follow-ups to this one, but I couldn't find them,
so I'll respond to this (apologies to Julian :-). I noticed recently,
perhaps in P4, that Juli Mallett had introduced a "platform" config line
for configuration files. It made me wonder whether what we shouldn't
consider doing is adding a new "scheduler" directive, i.e.,:
scheduler 4bsd
#scheduler ule
Config(8) could be taught to allow at most one scheduler directive. It
would allow zero with a warning ("No scheduler defined at compile-time;
one must be loaded as a module"). We'd either introduce a new class
similar to OPTIONS, or map the argument of scheduler directly to an
option, with the possible risk of getting some false positives in the
argument validity checking.
While it may well be that at some point we flip to using ULE, but since
the idea of pluggable schedulers comes up with relative frequency and
there is interest in scheduler research, maintaining the ability to easily
plug schedulers sounds like the right strategy, so formalizing it to
improve the ease-of-use factor would be useful.
(For the humor impaired, we could also use "sched" instead of "scheduler"
above.)
Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org Network Associates Laboratories
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