Re: overview of using hotplug in initrd

[iSteve <isteve@rulez.cz>]

On Mon, 27 Feb 2006 12:06:31 -0600
"Aaron Griffin" <aaronmgriffin@gmail.com> wrote:

> On 2/25/06, iSteve <isteve@rulez.cz> wrote:
> > I'm sure I'll be shouted at for being obsolete, but my way, in InitRD, is
> > to use now discontinued hotplug-ng (courtesy of Greg Kroah-Hartman, whom I
> > thank for great software) for hotplugging and to detect existing hw, I use:
> > for als in `cat /sys/bus/*/devices/*/modalias`; do modprobe $als; done
> 
> Hmmm, that works for you?  Here, I loop over
> /sys/bus/pci/devices/*/modalias and then do some ide/scsi specific
> detection.  That is, I have no support for that stuff built into the
> kernel (you may be different).
> Also, it's a hair faster to build a module string in a loop and call
> "modprobe -a", as modprobe only needs to read the config files once,
> thus one call is better than ~10.
> 
> iSteve, I'm curious as to your startup times, mine seem a tad slow,
> and I'd be interested in profiling this sort of stuff to make it
> faster.

Fast. With a generic, very very modular kernel, it spends only about two or
three seconds in initrd; most of the time is taken by IDE drives detection.

I, however, use a significant trick; I run the modprobes in a paralel fashion,
since the I/O wait is what takes so long.

 -- iSteve


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