[Torsion-announce] Torsion 0.0.18 released

[Dan Helfman]

Here's the changelog:

torsion 0.0.18 (Mon, 06 Dec 2004 09:15:04 -0800)
  * switched to a new faster checkpointer
  * wrote a keyboard driver
  * added a very basic command shell
  * implemented a unit test framework

Firstly, thanks are due to Travis Geiselbrecht for general help, Lee 
Salzman for debugging wizardy, and Geoffrey Plitt for work on the shell 
and some good discussions.

The biggest change in this release is also the change that is probably 
least visible to any potential user: a fairly large overhaul of the 
memory checkpointer. Specifically, the mechanism by which dirty pages 
are gathered used to involve taking out a global lock and then spidering 
through the page tables on every checkpoint. Lee pointed out that a much 
better approach would be to make all persistent virtual pages start out 
as copy-on-write, and then trap any page write faults to determine which 
pages are dirtied between each checkpoint. I finally got around to 
implementing this method for the 0.0.18 release, and, after more than a 
bit of debugging, it turned out to work quite well.

The keyboard driver and basic shell allow the user to enter very simple 
commands to get the status of various Torsion sub-systems. I currently 
use the shell as more of a debugging and diagnostic tool than anything, 
a temporary solution to be eventually replaced with a real shell, 
perhaps some sort of real programming language.

The unit test framework is also very simple, but could be used to write 
some very real unit and functional tests, which Torsion needs especially 
at this point in its development.

Anyway, those are the highlights. In the effort to update the 
checkpointer, many other sub-systems were modified and improved, but 
apparently nothing noteworthy enough to make the release notes.

As for the future? Well, in the near term, Torsion could do with truly 
persistent tasks, which have been on the to-do list for a while now. 
Persistent tasks would allow you to fire up some application (say, a 
game or text editor), and then reboot, only to continue exactly where 
you left off in that particular task.

Additionally, William Rubel has generously offered some of his expertise 
in working on Torsion's documentation, which I've really got to take him 
up on now that 0.0.18 is out the door.

And as always, I encourage anyone with questions, ideas, or comments to 
post on the torsion-dev mailing list.

--
Dan Helfman <address@hidden>
http://torsion.org/