Date: Sun, 8 Jun 2003 16:38:36 -0700 (PDT) From: Doug Barton <DougB@FreeBSD.org> To: Terry Lambert <tlambert2@mindspring.com> Cc: Matthew Dillon <dillon@apollo.backplane.com> Subject: Parallelizing rc (Was: Re: Making a dynamically-linked root) Message-ID: <20030608160735.I5603@znfgre.qbhto.arg> In-Reply-To: <3EDD7CFA.4795FB99@mindspring.com> References: <20030602171942.GA87863@roark.gnf.org> <xzpznl02nry.fsf@flood.ping.uio.no><3EDD7CFA.4795FB99@mindspring.com>
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On Tue, 3 Jun 2003, Terry Lambert wrote:
> People try to pretend that the dependencies that exist are
> between programs, but they're actually between service
> providers and service consumers, and largely independent of
> the programs providing the services. On top of that, the
> dependencies tend to be both hard and soft, e.g. it's possible
> to continue to offer a degraded service, rather than failing
> outright, if some dependent services aren't there (e.g. you
> can log by IP address if DNS isn't up to provide reverse
> name mappings to look pretty in your logs, etc.).
A lot of people have suggested that parallelizing rc ought to be an easy
thing to do, especially with the new rc system in place. However, we've
actually looked at doing that, and in practice it turns out to be much
more difficult than it sounds. Terry's point here is well taken, and
shouldn't be trivialized.
The rc team has regular conversations about improving the dependency
ordering, and they generally go 'round in circles and land in the same
location, since what we have now works, and historically changes have led
to the dreaded "unpredictable results" for edge cases.
All that said however, if someone really wants to take up this banner,
please feel free. I'd appreciate it if you'd coordinate with the folks at
freebsd-rc@yahoogroups.com, but it's not a requirement. Before committing
to the tree however, please post your work for review, and make sure it
gets lots of testing with lots of different situations.
Doug
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