Feedback for readahead

Armin Berres trigger+debian at
Tue Jan 15 17:32:45 UTC 2008

On Tue, 15 Jan 08 16:25, Petter Reinholdtsen wrote:
> [Armin Berres]
> > No, I don't use the preload package. You can find the bootcharts here:
> >
> Thank you.  Those do look strange, indeed.  Did the profile step
> update both the files in /etc/readahead/?  Do you have /var/ or /usr/
> on a separate partition from /?  You did profile readahead to match
> your machine, right?  The fact that the boot is still reading files
> from disk even after readahead loaded the files make me believe that
> you might be using the default files, and those are not adjusted to
> your needs.

Yes, both files we're recreated on this box and I have neither /var/
nor /usr/ on a seperate partition.
Could one win anything by preloading in the background and starting e.g.
udev in the meanwhile? I have to admit that I have no idea if this would
make any sense wrt a short boot time.

> > Apart from preloading the boot sequence it would be quite
> > interesting, to preload the desktop startup as long as the DM is
> > shown and the user didn't log in. kdm has an option to start and
> > stop such a script automatically. Maybe it would make sense to give
> > readahead a try in this scenario, too? One just need to find a sane
> > way, to figure out which files should be preloaded. Maybe loading
> > all files which are accessed in the first 20 seconds or so...
> This is the focus of the preload package.  It loads the files used by
> the desktop, among other things.  Because of this, one must disable it
> while profiling readahead, to avoid readahead believing that the files
> loaded by preload for the desktop is needed during boot, as it would
> lead to the desktop files being loaded as part of the boot and thus
> slow down the boot.

I think I tried this once and it also slowed down the boot duration. The
trick here is IMO to start preloading the desktop stuff, when the
computer is idle and stop again if the user logs in. I don't want
something to preload Firefox or Open Office while booting.
I think it would be possible to use readahead quite easily in this
scenario, too. Maybe I'll play a bit with it when I have some spare
time. If I should be successful you will here from from me.


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