Re: Directory deltification

Stefan Fuhrmann <stefanfuhrmann_at_alice-dsl.de> writes:

> As of r1224839, FSFS now supports directory deltification.
> Please review the changes and run tests against different
> repositories so that we get a better idea of what the costs
> and benefits are. As soon as I'm back home, I will run tests
> against the Apache and KDE repositories.
>
> So far, I ran tests against the rather small TSVN repository.
> It seems that we get 50% more capacity / 33% size savings
> for 0 .. 20% CPU overhead.

I've been testing this with the old CollabNet Subversion repository, the
first 40,515 Subversion revisions, on my Linux laptop:

The db/revs directory (unpacked) is 320MB instead of 490MB.
Loading takes about 12% more CPU.
Dumping takes about 22% more CPU.

which matches your results. Packing removes about 85MB for both
repositories.

There are operations where reading the directory representations is more
dominant. 'svn log' on a path inside the repository uses 100% more CPU.

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