On Thu, Sep 29, 2016 at 11:55 AM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> For the kernel, just the *math* right now actually gives 12
> characters. For current git it actually seems to say that 8 is the
> correct number. For small projects, you'll still see 7.
Sorry, the git number is 9, not 8. The reason is that git has roughly
212k objects, and 9 hex digits gets expected collisions at about 256k
objects.
So the logic means that we'll see 7 hex digits for projects with less
than 16k objects, 8 hex digits if there are less than 64k objects, and
9 hex digits for projects like git that currently have fewer than 256k
objects.
But git itself might not be *that* far from going to 10 hex digits
with my patch.
The kernel uses 12 he digits because the collision math says that's
the right thing for a project with between 4M and 16M objects (with
the kernel being at 5M).
So on the whole the patch really does seem to just do the right thing
automatically.
Linus