Planning for a 3.9 beta

[Linus Torvalds]

On Sat, Nov 2, 2013 at 7:24 AM, Dirk Hohndel <dirk at hohndel.org> wrote:
>
> Finally, Linus... have we given up on a new file format?

Largely. It got ugly.

The saving side is very XML-specific, and while I had a hack that
saved in the new format, being able to choose old/new format (so that
we could continue to export as XML for legacy reasons and for people
who wanted to do XML transforms) was painful as hell.

On the loading side, it actually looked like switching to expat or
some simpler xml library migth avoid some of the overhead, but since
we depend so much on the xslt transforms for input conversions from
other formats, that just isn't an option either.

I do have a patch that speeds up XML loading by about 10-15% on my
machine by just trimming the fat from our own code. It's fairly large,
mainly because it switches our node name around, so all the MATCH()
lines get trivially edited. But all the libxml overhead remains, and
the file size doesn't change.

Using compression makes the file sizes much smaller (gzip isn't very
good for our files, but xz kicks ass on them). xz in particular is
pretty slow on the compression side, though, making saving noticeably
slower. Loading (decompression) isn't as bad, but it sure doesn't
speed up loading (except possibly if you have some seriously slow IO
;)

                 Linus