Bootup speed for F8

David Zeuthen david at fubar.dk
Sat Dec 1 06:23:09 UTC 2007


On Fri, 2007-11-30 at 21:50 -0800, Jesse Barnes wrote:
> On Friday, November 30, 2007 6:06 pm Dimi Paun wrote:
> > On Fri, 2007-11-30 at 11:18 -0500, Bill Nottingham wrote:
> > > 1) bootchart weirdness (as it's from when bootchart starts)
> > > 2) hotplug issues with a driver in the initrd not initializing
> > > right
> >
> > Well, maybe, but I think it's a common problem:
> >     http://lattica.com/pub/bootchart-20071130-f8.png
> >
> > In my case, that initial time is close to 11s! And mind
> > you, it's no bootchard weirdness, I've always noticed it.
> 
> Yeah, I'm seeing the same thing, ~10s on one machine and ~15s on 
> another.  I briefly looked at the nash scripts and hotplug code in the 
> initrd.  It looks like we spend a lot of time waiting for the kernel to 
> generate hotplug events and settle down the devices... I'm not sure how 
> much of it could reasonably be trimmed, maybe comparing to a non-initrd 
> config would make sense?  I think this is pjones' stuff, so there are 
> probably good reasons for the way things are.

In the perfect world (and on 99% of the other distros), the initramfs
can exit to real user space as soon as the root device is mounted.

I know that on Fedora (at least in the past) we play some really ugly
tricks to make sure that the kernel names (e.g. sda, sdb etc.) for the
devices are in a specific order (scsi_wait_scan.ko etc.). Seems
literally like a waste of time; better fix the rest of the OS not to
rely on things like kernel names.

Then again, I haven't looked at this for some time... It would be
interesting to compare to other distros like SUSE, Debian and Ubuntu to
see how much slower or faster we are.

       David





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