Re: profile-fast is failing in my Git 2.2.1 build from tar in a Git repo

[Jeff King <peff@peff.net>]

On Mon, Jan 12, 2015 at 04:08:28PM -0500, Jeff King wrote:

> > I do not think profile build is prepared to be run without having
> > our history (after all, it is not test_perf_create_REPO_from, not
> > test_perf_create_source_directory_of_git_from).  It wants to create
> > a repository that hosts a reasonably sized but not too big a
> > project, i.e. us.
> > 
> > The safest and cleanest fix would be to make sure that the said
> > function checks if $source/.git is a repository, perhaps?
> 
> Hmph. We already dealt with this once in 93b5393 (Makefile: make perf
> tests optional for profile build, 2014-08-19). That check explicitly
> looks for ".git" (and not checking that we are in an outer git repo), so
> I am not sure why it is kicking in at all. But probably the fix should
> go there.

Oh, I see. It is because Paul is using profile-fast, which does not have
that check. And I did not add it as part of 93b5393, because it would
not make sense. If you do not do the perf tests, then profile-fast is
literally doing nothing. :)

I think the right solution is either:

  1. Switch to using "make profile", which will use the regular test
     suite to gather data, and skip the perf tests.

  2. Set GIT_PERF_REPO to some representative repo of your choice for
     gathering profiling data (it does not have to be git.git at all,
     but it is probably more useful if it is not a tiny toy repo).

We _could_ teach the perf code to look upwards for a surrounding repo
with `git rev-parse` rather than looking for ../../.git. But there is no
guarantee that the repo we find would actually be a useful one for doing
perf tests. I'd just as soon leave it as-is, and have people specify a
useful repo via GIT_PERF_REPO if they have one.

-Peff