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Re: faster boot



Re: Re: faster boot [Thomas Hood <jdthood@yahoo.co.uk>, Tue, Oct 21, 2003 at 05:08:11AM +0200, <1066705689.1721.2502.camel@localhost>]
> System V initscripts must not return until the services they start
> are ready to use.  Otherwise running initscript Y after initscript
> X from /etc/rc?.d/ doesn't guarantee that Y can make use of X.
> Providing such guarantees is the whole point of the system.  (Or
> have I somehow missed your point?)

Scripts having the same serial number cannot depend on each other, so
these can be started in parallel. As there are fairly many S20 and S99
scripts in /etc/rc2.d, this might be a good thing.

> If you are going to try to speed up boot by relaxing the rule
> that services are started one at a time then you have to do this
> in such a way that the interdependencies of services are still
> satisfied.  You have a choice between (1) adding "needs"/"provides"
> information to the system so that it knows which pairs of initscripts
> to serialize, and (2) changing initscripts so that they are able to
> wait until prerequisite services have become available.  There are
> other possibilities, too ...

I've been thinking for a while to use a Makefile for that, then you get
parallelizing for free with 'make -j'. It should be easy to set up the
rules for starting services; stopping might be more complex (how to
'reverse' a Makefile?).

Christoph
-- 
Christoph Berg <cb@df7cb.de>, http://www.df7cb.de/
Wohnheim D, 2405, Universität des Saarlandes, 0681/9657944

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