Re: Debugging udevd startup time

[Greg KH <greg@kroah.com>]

On Wed, May 20, 2009 at 07:25:16PM +0300, Ozan Çağlayan wrote:
> Ozan Çağlayan wrote:
> >> The log shows 1.8 seconds, bootchart might not show too much here.
> >>   
> >>     
> >
> > I've just tried on a tiny sony vaio centrino laptop which loads 71
> > modules during boot. Its log shows 1.4 seconds between the first and the
> > last event.
> >   
> 
> 3.2 seconds on a recent Dual Core MacbookPro5,1 which loads 52 modules
> during boot. It seems that the gap can oscillate very brutally from one
> system to another one.

That sounds like a modprobe issue, not a udev one.

There have been some new kernel changes to make this go faster, perhaps
you need to integrate them.  Also realize that loading 52 modules will
take a lot of time, just due to all of the in-kernel lookups that are
necessary to accomplish this.

Perhaps you might wish to cut down on this large number, if you have
everything as modules, you loose some of the new kernel speedups that
have happened with async probing of devices which can not happen if the
drivers are in modules.

Look at the recent moblin releases for examples of how to speed this up.

good luck,

greg k-h