announce: readahead-1.4

[David Zeuthen]

On Wed, 2007-03-07 at 17:38 -0600, Callum Lerwick wrote:
> Lets not get crazy
> here. ext3 does a decent job of not fragmenting files unnecessarily, can
> we really gain much more than the current readahead solution?

Yes we can. See point 8. of

http://www.redhat.com/archives/fedora-devel-list/2004-November/msg01374.html

> We could designate the first ext3 block group (actually should make the
> number configurable) as the "hot" area. Patch the kernel so it avoids
> doing any allocations in the "hot" group(s) except as a last resort.
> Then write a tool to move files into the "hot" area somehow, possibly
> with help from the kernel.

It's been two and half years ago since I showed that even a poor hack of
"defragging" the file system makes booting around 15-20 seconds faster
and I'd be surprised if the same isn't true today. It would be useful if
some of the ext3 developers actually read fedora-devel-list and
commented on this.

     David