hi folks,

the Unified Buffer Cache project that I've been working on forever
is finally almost ready to integrate into the netbsd tree.
I've been running it on my main workstation for several weeks now
and I haven't had any problems in the last week.  before I commit
it to -current, I'd like to get a few other people to try it out
just to get a little better test coverage.

the testing that I've done includes FFS on these platforms:

	i386		various models
	sparc		sparcstation 4
	sparc64		ultra1
	alpha		pc164
	mips		decstation 5000/200
	powerpc		powermac 9500
	m68k		quadra 650, hp385
	arm32		shark
	vax		vaxstation 3100, vaxstation vlc, vaxstation 4000/90

and these other filesystems on at least one platform:

	mfs
	procfs
	kernfs
	ext2fs
	msdosfs
	cd9660

(lfs isn't working in -current at all right now, and I think it will need
 additional work to fix it to work with UBC even after the existing problems
 are fixed.  I'm not going to delay integration for that, tho.)


I'm currently distributing the code in the form of diffs against -current.
these can be found in ftp.netbsd.org:/pub/NetBSD/misc/chs/.  the diff
for a given day applies cleanly to -current on that day.  I try to make
a new diff every few days.  no, I'm not going to make another branch.
there is no kernel option for UBC, it's always on.  just apply the diff
and rebuild the kernel.  if you have increased the size of the buffer cache
you'll want to remove those options for a UBC kernel.

the difference you'll see is that you have lots of memory, most of that
memory will now be available to cache file data. right now at most
7/8 of RAM will be used to cache file data, but eventually the limit
will be tunable.

so, anyone who likes to try the latest and greatest, please try running
a UBC kernel and report your experiences either here or directly to me.

-Chuck