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Re: 1-second kernel

On Sun, 2008-12-21 at 01:26 -0800, NiftyFedora Mitch wrote:
> There are two places to pay critical attention to first:
>   A.  hardware initialization.
> For a system to boot all hardware has to be known in advance.
> NO probes that time out for this and that...  SCSI timers are LONG...
> No probe of USB this and that.
> To that end building a kernel with "your" devices built in it
> can help. Exclude any driver that you do not have hardware for.....

It strikes me that that sort of thing ought to be the default action any
time you install a kernel - auto customising to suit your hardware,
particularly the non-changing aspects of it (on board chipsets, and
things plugged into them, like internal hard drives).

Though I tend to favour the microkernel approach:  The kernel has the
bare minimum needed, you load extras as needed.  One motherboard with
the usual peripherals ought to only load a handful of modules, which
should be less elephantine than a kernel carrying hundreds of them.

But it should be something like:  Customise my system now (when
installing a kernel, or whenever deliberately invoked).  Subsequent
bootups will probably bootup the same way, so they can use your
preconfigurations, and don't need so much probing next time (find my
boot drive now, boot from it, poke around for other removable external
drives while booting, but don't delay booting while you look, since I've
already set what's needed to boot).  You still have various rescue
options to handle a system that fails to boot, so customising shouldn't
lock you out.

>   B. Network timers.
> Network timers are much longer than we all expect... Ensure that
> all name servers and network knowledge that can be "hardwired" is. No
> DHCP no discovery of name servers.   Snoop the net (dumb hub, second
> machine) and watch for timeouts and other traffic you do not expect.

This shouldn't really be a major bottleneck.  Your DHCP servers ought to
be quickly responsive.  If they aren't, then that's something else that
should be tackled.

Wireless is a pain, though.  It takes time for that to get organised,
and for some annoying reason, it takes longer to discover my wireless
router than it does to find the neighbour's.

> For example X11 takes a lot longer to start than I expect.. in part
> because the window manager desktop has all sorts of live buttons and
> widgets.

I find I sit there looking at GDM spinning its "wait a moment" indicator
for far longer than it should do.  Here, the full X starts faster than
GDM does.  I'm inclined to be suspicious about the superfluous feature
that loads different pictures at different times of day.  The previous
GDM, which didn't do that, was easily and conveniently reconfigurable,
and didn't drag its heels.

> Clean up as much as you can without X11 i.e. login on a simple text
> window... and use 'startx'...

If you have to log in, then start X manually, that's adding a delay.  So
I don't see a real benefit there.

I had considered the notion of not using GDM (thanks to *its* holding up
delay), starting in a text mode, and scripting something to start X as
soon as I log in.  However, my experience has been that without GDM and
Gnome (i.e. forgo one of them), and you find you're using a system
without sound, or network, or auto mounting, or something else that's
become dependent on one or the other of them.

[tim localhost ~]$ uname -r

Don't send private replies to my address, the mailbox is ignored.  I
read messages from the public lists.

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