[Arm-netbook] Debian boots in 0.87 seconds

[Luke Kenneth Casson Leighton]

On Wed, Dec 3, 2014 at 3:29 PM, Wookey <wookey at wookware.org> wrote:

> All that said, I'm sure that study of Debian and options for having
> standardised ways of improving boottime would be worthwhile. I bet
> there are things we could do to at least make this easier and possibly
> make things go faster _without_ undue loss of generality, especially
> as there has been a pile of change recently in the boot process (don't
> mention the war! :-)

 ... whatever you do, don't mention ze war :)

 yes.  wookey, there is *definitely* something that can be done,
unfortunately i lost the work back in 2006 (and would have to recreate
it).  basically udev right now creates hundreds of nodes and has to
"settle".

 this "settling" *can* be sub-divided into at least two groups.  you
can look in the udev event trigger location (somewhere in /sys) and
instead of "is empty subdirectory" use "grep sd* net* tty?" and other
tricks.

 in this way it's possible to have (at the very least) mounting and
networking come up a good few seconds *before* everything else.  you
*do not* need to delay networking or early mount just because 768
pseudo-ttys have to be created.

 and it _does_ take a long time because of udev spawning bash/dash
scripts, which then spawn more bash scripts... back in 2004 i think i
saw a stack of bash scripts *THIRTY DEEP* on a old Pentium 90 system -
it was something like *2 MINUTES* for udev to stop f******g about.

 whilst there have been many improvements in hardware
context-switching for x86 systems, other processor architectures *do
not* have such good context-switching (extreme case: ARM9 as you well
know) so on such systems the effects of the assumptions "everything
works fine on x86" are much more marked.

l.