Re: [Gnu-arch-users] Re: Why we might use subversion instead of arch.

[Miles Bader]

On Thu, Feb 26, 2004 at 07:51:29PM +0000, John Goerzen wrote:
> Setting up a local revision library is out of the question due to the
> apalling space requirements this would require.

Have you tried, using greedy sparse libraries?

I've _manually_ (cp -al + patch) kept _multiple_ hard-linked trees for every
kernel version since 2.5.35 or so, and the space requirements seems quite
reasonable (which makes sense -- the changes for each new revision are often
fairly large, but the complete tree is far, far larger).  I think (I'm not at
work right now) the sum of these hard-link trees, for a few hundred-odd
source trees, is about equivalent to 2-3 non-hard-linked source trees; I'll
look up the actual numbers when I get to work.

> Cached revs are used -- but that does no good for commits, which are the
> slowest operation.

I think for the kernel, cached revs are rather problematic anyway, since it's
so big; using a sparse+greedy revlib and --link (`tla get --link', and do
`tla changes --link' periodically) would probably be a lot better.

Clearly you're not going to be able to much with only a few hundred MB free
on your disk -- but this is true for kernel development in general unless you
spend a lot of time stressing over disk space management!  Bump it to 1-2GB,
and things become a lot more reasonable.

In my mind, the `.id problem' is actually the biggest thing; it'll be nice to
see how Robert's changes to optimize .id files to use inode-summaries work,
though in my mind, a change to using a different .id file representation
seems the most promising for the long term (the primary problem there being
to add some mechanism for file-specific diffing, since really want diffs on
`consolidate .id files' to use 0 context).

-Miles
-- 
In New York, most people don't have cars, so if you want to kill a person, you
have to take the subway to their house.  And sometimes on the way, the train
is delayed and you get impatient, so you have to kill someone on the subway.
  [George Carlin]