Active Block I/O Scheduling System (ABISS), version 2

Active Block I/O Scheduling System (ABISS), version 2

[Werner Almesberger]

The Active Block I/O Scheduling System (ABISS) is an extension of the
hard-disk storage subsystem of Linux, whose main purpose is to provide
a guaranteed reading and writing bit rate to applications.

http://abiss.sourceforge.net/abiss-2.tar.gz
md5sum 33c103dc503d1a393516f8bbf95e52bb
sha1sum def6ac2ce5ba1613c470cd0ca761f97cdc56f7ae

This release fixes a couple of serious bugs and adds exciting new
functionality:

 - the index bits to mask map of ABISS' copy of prio_tree was never
   initialized, which caused rare and quite obscure crashes in the
   elevator.

 - ABISS used to reference the super block to make sure that the
   latter doesn't go away until ABISS has removed the data structures
   hanging off it. This was of course completely useless, because one
   could still make the file system inaccessible. Worse yet, since
   the super block was still referenced, it wasn't committed to disk.

   We now use a umount notifier and always remove ABISS when the file
   system gets unmounted. (If it's mounted multiple times, the last
   umount counts.)

 - we're now using the 2.6.9 kernel. While this isn't exactly the
   greatest kernel in history, it's still a step forward. Since the
   various UML updates have been merged into 2.6.9, no separate UML
   patch is needed.

 - ABISS now also supports ext3. This still needs a little more
   testing, but in general looks good.

The detailed list of changes is below. For additional information,
please have a look at http://abiss.sourceforge.net/

- Werner

----------------------------------- CHANGES -----------------------------------

Version 2 (9-NOV-2004)
----------------------

Kernel:

- upgraded to 2.6.9
- fs/abiss/prio_tree.c:abiss_prio_tree_init: fixed invocation (reported by
  Benno van den Brink)
- added umount notifier, which ABISS uses to clean up when unmounting (instead
  of messing with the super block's reference count)
- fs/abiss/file.c: restructured get_block support to avoid calling out to file
  system's get_block function
- added experimental support for ext3
- fs/abiss/prio_tree.c: added functions for validation and analysis
- fs/abiss/file.c: made debugging printks less chatty

Tools:

- added new tool "ptree" to pretty-print binary trees
- rdrt sometimes printed the time since the epoch instead of the total run
  time

-- 
  _________________________________________________________________________
 / Werner Almesberger, Buenos Aires, Argentina     werner@almesberger.net /
/_http://www.almesberger.net/____________________________________________/