On Mon, Nov 12, 2018 at 11:21:51AM -0500, Jeff King wrote:
> No, but they don't even really need to be actual objects. So I suspect
> something like:
>
> git init
> for i in $(seq 256); do
> i=$(printf %02x $i)
> mkdir -p .git/objects/$i
> for j in $(seq --format=%038g 1000); do
> echo foo >.git/objects/$i/$j
> done
> done
> git index-pack -v --stdin </path/to/git.git/objects/pack/XYZ.pack
>
> might work (for various values of 1000). The shell loop would probably
> be faster as perl, too. :)
>
> Make sure you clear the object directory between runs, though (otherwise
> the subsequent index-pack's really do find collisions and spend time
> accessing the objects).
Below are my results. They are not as comprehensive as Ævar's tests. Similary I
kept the loose objects between tests and removed the packs instead. And I also
used the "echo 3 | sudo tee /proc/sys/vm/drop_caches" trick :)
This is with git.git:
origin/master jk/loose-object-cache
256*100 objects 520s 13.5s (-97%)
256*1000 objects 826s 59s (-93%)
I've started a 256*10K setup but that's still creating the 2.5M loose objects.
I'll post the results when it's done. I would expect that jk/loose-object-cache
is still marginally faster than origin/master based on a simple linear
extrapolation.
