isofs now uses an in-memory directory listing built on-the-fly instead
of parsing the ISO 9660 data structures over and over for almost every
request. This yields huge performance improvements.
The directory listing is allocated dynamically, but Minix servers aren't
normally supposed to do that because critical servers would crash if the
system runs out of memory. isofs is quite frugal, won't allocate memory
after having the whole directory tree cached and is not that critical
(its most important job is to serve as a root file system during
installation).
The benefits and elegance of this scheme far outweights this small
problem in practice.
Change-Id: I13d070388c07d274cbee0645cbc50295c447c5b6
Known limitations:
- comment for now testisofs, as iso9660fs is known to be broken.
Benefits:
- near 3x speed improvement on C++ code compilation, bringing down
make build to from 44min down to 21min.
- Allows for X applications to work properly, which should be available
in near-term future through pkgsrc for 3.3.0.
Change-Id: I8f4179a7ea925ed381642add32cfd8c5822217e4
