Re: [RFC] kernel facilities for cache prefetching

On Tue, 2006-05-02 at 16:53 +0800, Wu Fengguang wrote:
On Tue, May 02, 2006 at 10:30:17AM +0200, Arjan van de Ven wrote:
one interesting thing that came out of the fedora readahead work is that
most of the bootup isn't actually IO bound. My test machine for example
can load all the data into ram in about 10 seconds, so that the rest of
the boot is basically IO-less. But that still takes 2 minutes....
So I'm not entirely sure how much you can win by just attacking this.

Yes, I find it hard to improve the boot time of the init.d stage.
However, it is perfectly ok to preload all GUI staffs during that
timespan, by overlapping CPU/IO activities.

fwiw fedora even loads a bunch of GUI apps into memory already


Another interesting approach would be to actually put all the data you
want to use in a non-fragmented, sequential area on disk somehow (there
is an OLS paper submitted about that by Ben) so that at least the disk
side is seekless...

You are right, reducing seeking distances helps not much. My fluxbox
desktop requires near 3k seeks, which can be loaded in the 20s init.d
booting time. But for KDE/GNOME desktops, some defragging would be
necessary to fit them into the 20s time span.

or just move the blocks (or copy them) to a reserved area...


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/