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RE: svn edit

From: Harvey, Edward <Edward.Harvey_at_patni.com>
Date: Thu, 30 Oct 2008 15:34:48 -0400

> On Thu, Oct 30, 2008 at 1:19 PM, Branko Čibej <brane_at_xbc.nu> wrote:
> > Harvey, Edward wrote:
> >> For a simple "find" I think this is typical performance:
> >>
> >> 100,000 files in 10 sec cold cache
> >> 1,000,000 files in 3 sec warm cache.
> >>
> >> I think if this performance can be achieved for "svn st"
> and "svn up" it's acceptable. I do, however, doubt being
> able to achieve that while walking the tree with svn -
> because git failed to achieve it.
> >
> > Oh I say, that's a truly obnoxious statement. Second of
> all, a version
> > control system has a lot more to do than a simple find. But
> first of
> > all, it implies that git is the unattainable grail of software
> > perfection. Perish the thought.
> Brane: clearly you're both ugly and stupid. :-)

Alright, let's just cool it everyone. There is a little bit of truth all around.

It's true a versioning system *does* have a lot more to do than simply peek at all the files, and that's why both git and svn take an order of magnitude longer to walk a tree than a simple tree walker. The versioning system must perform "open" and "read" and "seek" or whatever operations... And do some thinking... This is why I am a skeptic about svn or git or anyone being able to come close to the performance of simply walking the tree. But there is still a lot of ground to be gained in terms of performance boosting.

Git developers & users are proud of their performance, and Linus is one of them. So whatever inefficiencies they have, I'm sure it's not blatant and shameful. This is why I think the performance of git is a realistic upper-bound expectation for performance of a versioning tool that walks the tree. Maybe it can be beat. But it's doubtfully an order of magnitude.

Then again, if the WC metadata were in ram already, the most expensive thing remaining would be to walk the tree. So theoretically it might be possible to achieve the tree-walking performance of a simple tree walker. Nobody here has tried it yet (AFAIK).

So let's agree to let the WC NG come about, and see how well it does. If it somehow destroys the performance of git, and comes close to the speed of a simple walk, then probably nobody will have any further complaints.

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Received on 2008-10-30 20:35:12 CET

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