Re: Any tips for improving the performance of cloning large repositories?

From: Alex Bennee <kernel-hacker@bennee.com>
Date: Dec 16, 2011, 18:37 UTC
Message-ID: <CAJ-05NNcORg2H_j3g-h-eDXuuGit_hNH6PG9tNq30QJwJMAPWg@mail.gmail.com>
In-Reply-To: <7vzkesigw9.fsf@alter.siamese.dyndns.org>

On 16 December 2011 17:08, Junio C Hamano <gitster@pobox.com> wrote:

Show 9 quoted lines

> Alex Bennee <kernel-hacker@bennee.com> writes:
>
>> Well that's counter intuitive....
>>
>>  - reverting the original repo to one big pack speeds up the clone
>>  - adding a --local --reference mirror slows it down
>
> Neither is. Read what "--local" says in the help text of clone. It
> disables the git aware clever optimization.

OK that's not how I read the man page:

       --local, -l
           When the repository to clone from is on a local machine,
this flag bypasses the normal "git aware" transport
           mechanism and clones the repository by making a copy of
HEAD and everything under objects and refs directories.

So this says it skips "git aware" (whatever that means)

           The files under .git/objects/ directory are hardlinked to
save space when possible. This is now the default when
           the source repository is specified with /path/to/repo
syntax, so it essentially is a no-op option. To force
           copying instead of hardlinking (which may be desirable if
you are trying to make a back-up of your repository),
           but still avoid the usual "git aware" transport mechanism,
--no-hardlinks can be used.

And this says that objects on the local file-system are hardlinked (rather than copied) which I assumed was a optimal approach.

       --no-hardlinks
           Optimize the cloning process from a repository on a local
filesystem by copying files under .git/objects
           directory.

I'm not sure how this is an optimization? This means more copying rather than linking right?

-- 
Alex, homepage: http://www.bennee.com/~alex/
http://www.half-llama.co.uk