To:	linux-kernel@vger.rutgers.edu
Subject: revision control for the kernel (BitKeeper)
From:	lm@bitmover.com (Larry McVoy)
Date:	Sun, 21 Feb 1999 01:14:26 -0800

Most of you know we've been working on the next gen revision control for
the kernel for a while now.  For those of you who don't know, BitKeeper
is an Open Source distributed revision control system which I claim is a
substantial step forward from CVS.  http://www.bitkeeper.com and
http://www.bitmover.com/talks/linuxworld have more info.

It's nearing a state where it could be put into use but there are some
open issues.  I'd like to discuss these issues, some of which are Linux
specific, with people who are interested in this sort of thing.

We could discuss it here, but I've set up an alias, kernel@bitmover.com,
which is probably a better place.  It's a majordomo alias.

I've added some of the core kernel developers to that list, other people
should add themselves.  I'm especially interested in having some people
with low bandwidth connections and disk space concerns be on the list.
The bandwidth isn't a big problem, but the disk space is an issue.
It does use more space to have this stuff under revision control and I 
want to discuss that to see if it is acceptable to the community.  Here's
an example: consider just the Historic kernels (0.1 .. 0.99.15, 38 in all).

	Size	What
	17M	All 38 tarballs gzipped
	11M	All 38 versions checked into BitKeeper
	1.8M	All 38 versions checked into BitKeeper and bzip2-ed
	 .5M	The 0.99.15 tarball, gzipped

So there is good news and not so good news.  The good news is that if 
we are just talking tarballs, we can have all the history in less space
than all the tarballs put together.  And about 10x less space if we are
talking about a tarball of the repository.  The bad news is that I have
a feeling that we might be looking at a 100-200MB repository for all the
history going back to the beginning.  We haven't converted all of it yet,
I'll let you know the results as soon as we do.

Anyway, I'd love to get your thoughts, please join the list and we'll
figure it out.

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