On Dec 2, 2009, at 8:35 AM, Jason Corley wrote:

> That's actually somewhat surprising, my recollection is that
> bsdiff/bspatch is quite heavily used for freebsd binary updating via
> freebsd-update(8) and also for the ports tree if you use portsnap(8).
> Jason
> P.S. http://www.freebsd.org/cgi/man.cgi
> 

Yup. But the patch file generated by bsdiff already uses bzip2
for several sections. And the win with bsdiff (and bzip2 iirc)
is the Burrows-Wheeler transform for efficient suffix sorting.

All I've done is remove one of several B-W transforms. B-W transforms
are difficult to parallelize and memory hungry afaik too. The
cost of generating the patch is seldom cited (see the PhD thesis,
perfomance is described as O(...) theoretically, rather hard to
see KISSy wall clock times in the theseis).

Note that Courgette disassembles executables before deltafying. All
seems to depend (unsurprisingly) on what plaintext is used.

YMMV, everyone's does.

73 de Jeff