Re: Interaction of udev with the init subsystem

[Greg KH <greg@kroah.com>]

On Mon, Mar 02, 2009 at 11:09:39PM +0200, Ozan Çağlayan wrote:
> Hi,
> 
> I'm maintaining the udev package for Pardus, a GNU/Linux distribution
> mainly developed in Turkey.
> 
> After doing some investigations of the startup time on our distribution,
> I've figured that udev related invocations takes a lot of time.
> 
> 1) The startup of the daemon is quick enough, no problem here,
> 2) The first trigger+settle takes ~4.5 seconds to complete.
> 
> We're currently using udev-126 but I also tried 137, and the performance
> is quite the same.

It's the modprobe stuff that is taking most of the time, right?  That's
not udev.

> I wonder what are the points that a distribution packager/maintainer should consider
> when starting/stopping udev for having the best startup time.
> 
> My second question is about the orphaned rule files left in /dev/.udev
> after triggering the event processing on a read-only root filesystem. I'm succesfully
> collecting those rules, moving them into /etc/udev/rules.d and recalling trigger
> after mounting the root filesystem read-write. If I don't retrigger,
> no dvd, cdrw, etc. symlink are created in /dev if the optical drive contains
> a media during boot. Retriggering here takes ~0.11 seconds.
> 
> It would be very nice to have a detailed documentation for udev beside rule writing stuff.

Patches are always gladly welcome :)

thanks,

greg k-h