Re: very slow cherry-pick'ing (old-2.6-bkcvs tree)

Erez Zadok schrieb:

Our group maintains Unionfs on the latest -rc kernel, but we also maintain
several backports going all the way to 2.6.9.  Once we complete the
development and testing of a feature/fix in -latest, we cherry-pick those
commits to older backports, and test those.  When I cherry-pick from -latest
to my 2.6.{22,21,20,19,18} repositories, it works reasonably fast.  But when
I cherry-pick to my 2.6.9 tree, it runs about 20 times slower!  Why?  Is
there anything I can do to inspect what's going on and perhaps speed up the
cherry-picking process?

Some info:

My 2.6.{18,19,20,21,22} trees were cloned from

   git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-2.6.<N>.y.git

My 2.6.9 tree, however, was cloned from

   git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/old-2.6-bkcvs.git

after which, I truncated the tree (git-reset) to Linus commit which read
"Linux 2.6.9-final".

I *think* that the reason for this is that those repositories don't have any 
commits in common (but I don't have clones to verify my claim). Since 
cherry-pick does merge-recursive, it tries to find a suitable merge base, 
but since there is no history in common, it walks both histories all the way 
down only to find that there is no possible merge base.

You could improve the situation if you graft the histories together:

   echo $first_commit_in_2.6.12 $suitable_commit_in_bkcvs > .git/info/grafts

-- Hannes