Re: [PATCH] Put sha1dc on a diet

Linus: I would be surprised, the dependencies should be automatically determined.

BTW Did you make local changes to this perf branch? Specifically did you disable the safe hash mode that is on by default? Because if you did not, it might also be something else as all three hashes below are the same.

-- Marc

----- Original Message -----
From: "Linus Torvalds" <torvalds@linux-foundation.org>
To: "Marc Stevens" <marc.stevens@cwi.nl>
Cc: "Jeff King" <peff@peff.net>, "Dan Shumow" <danshu@microsoft.com>, "Junio C Hamano" <gitster@pobox.com>, "Git Mailing List" <git@vger.kernel.org>
Sent: Monday, March 13, 2017 9:20:02 PM
Subject: Re: [PATCH] Put sha1dc on a diet

On Mon, Mar 13, 2017 at 1:12 PM, Marc Stevens <marc.stevens@cwi.nl> wrote:

Unrelated side note: there may be some missing dependencies in the build infrastructure or something, because when I tried Jeff's script that did that "test the merge and the two parents", and used the pack-file of the kernel for testing, I got:

  5611971c610143e6d38bbdca463f4c9f79a056a0
/home/torvalds/v2.6/linux/.git/objects/pack/pack-153bb8cd11846cf9a27ef7b1069aa9cb9f5b724f.pack

  real 0m2.432s
  user 0m2.348s
  sys 0m0.084s

  5611971c610143e6d38bbdca463f4c9f79a056a0
/home/torvalds/v2.6/linux/.git/objects/pack/pack-153bb8cd11846cf9a27ef7b1069aa9cb9f5b724f.pack

  real 0m3.747s
  user 0m3.672s
  sys 0m0.076s

  5611971c610143e6d38bbdca463f4c9f79a056a0 *coll*
/home/torvalds/v2.6/linux/.git/objects/pack/pack-153bb8cd11846cf9a27ef7b1069aa9cb9f5b724f.pack

  real 0m5.061s
  user 0m4.984s
  sys 0m0.077s

never mind the performace, notice the *coll* in that last case.

But doing a "git clean -dqfx; make -j8" and re-testing the same tree, the issue is gone.

I suspect some dependency on a header file is broken, causing some object file to not be properly re-built, which in turn then incorrectly causes the 'ctx2.found_collision' test to test the wrong bit or something.

                 Linus