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Re: Boot poster challenge



On Sat, 2004-11-13 at 12:49 -0500, Christopher Hotchkiss wrote:
> IBM did some work regarding this recently.
> http://www-106.ibm.com/developerworks/linux/library/l-boot.html?ca=dgr-lnxw11-obg-BootFast
> The biggest set of problems is figuring out what can be parallelized,
> and what needs to be sequential. Personally I think that starting up
> an xserver is not the best way to ensure a speedy boot process. We do
> have bootsplash availible.
> 
> You can also look at the work that gentoo has done in this area
> http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=2&chap=4 .
> 
> Their initscripts allow for dependencies which allows for an easily
> maintainable parallelized boot process. Unfortunately their runlevels
> do not conform to either LSB or POSIX, I forget which one, but they do
> work quickly.

My point is basically to move away from "is rhgb a bottleneck", 
"would parallelization help?" speculation, and have a single graphical
display that can immediately provide those answers.

To me, the BootFast article really is a bit of a disappointment. It ends
with the cop-out paragraph: (*)

  The effectiveness of this technique depends on the number of services 
  that need to be run as well as the time it takes for each service to 
  run. The degree of parallelization possible is controlled largely by
  the dependencies between services. It may be that using this technique
  makes little improvement for some systems, while for others, it could
  have a dramatic impact on boot speed. This can be explained by the
  fact that each system has a different set of services enabled, and
  each of these services takes differing amounts of time to run. Once
  again, to use this technique, you need to establish the dependencies
  between the services you use for your particular system.

And doesn't provide any numbers about what speedups the author achieved.
Did the author not measure anything? Did the author not get any speedup
on his system? Who knows. Having before and after graphs would let you
not only see whether parallelization helped, but see why it helped,
or why it didn't help, and what would need to be fixed to make it help.

Thanks for the pointers,
						Owen

(*) Admittedly the article is really more of a tutorial than a
    scientific paper.

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