[llvm-dev] [RFC] One or many git repositories?

Bruce Hoult via llvm-dev llvm-dev at lists.llvm.org
Sat Jul 23 14:49:58 PDT 2016


On a decent machine, on ethernet from an laptop sharing its WIFI, in a flat
in Moscow ... two minutes and four seconds.

The actual .git directory is 523 MB. My total checkout is bigger than yours
(1.1 GB), presumably because my disk has bigger clusters.

Using 'git clone --depth 1 https://github.com/joker-eph/llvm-unified' (i.e.
without history ... but you can build head from it), it took 26 seconds to
download 79.62 MB and the whole directory is 604 MB.

llvm is 202 MB, clang 117 MB, and compiler-rt 35 MB. Not including the
other stuff would only save about 170 MB in the checkout (also savable with
a sparse checkout)  and about 30 MB in the .git directory.

Also, running ...

git repack -a -d -f --depth=250 --window=250

.. on the original 523 MB .git checkout reduced it to 449 MB. This took
5m44s on an i7 6700K and needs to be done only once, before the initial
push to github. Every user will then benefit from 74 MB of saved disk space
and network bandwidth on the existing history, forever.


On Sat, Jul 23, 2016 at 11:38 PM, David Chisnall via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> On 23 Jul 2016, at 03:39, Mehdi Amini <mehdi.amini at apple.com> wrote:
> >
> > I forgot to mention that I pushed the result there:
> https://github.com/joker-eph/llvm-unified/tree/cheri-unified
> > (History:
> https://github.com/joker-eph/llvm-unified/commits/cheri-unified )
>
> Thank you very much for doing this!  I’m now convinced that there’s a
> clean way to move from existing git clones to the unified repository.
>
> I think that we do need some decent documentation for how people with
> clones of the existing github.com/llvm-mirror repos produce a unified
> repository that they can then merge from upstream, but it looks pretty nice.
>
> It will require a bit of effort for us to update various scripts, CI jobs,
> and so on to make use of this, but it looks as if the end result will be a
> lot easier to work with and worth the transition pain.
>
> On a fast machine with a decent Internet connection, a fresh clone of this
> repo takes about one minute, 40 seconds, transfers 458.56MB and produces a
> directory that uses 876MB of disk space.  These numbers all look very
> reasonable.
>
> David
>
>
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