GCACHE -- what's it for?

[Geoff Fritz]

I noticed the presence of the geom_cache module recently.  Very little
available in the archives on what it's used for.

Found a post by pjd@ with a link to a tarball containing a man page:

"The gcache utility is used for setting up a clean cache in front of the IDE
controller on one disk."

(btw, where do I post to get this man page included in the release?
freebsd-doc?  I'm running 7.1-RC1 and the man page is absent.)

I set up a test device with it, and noticed that the disk did a lot of
thrashing when it was being written to, moreso than normal.  Is the purpose of
this module to ensure that when the gcache provdider says the write was made
it was in fact 100% written to the physical disk (or at least accepted by the
next layer down)?

Thanks for the info.

-- Geoff