Re: What's cooking in git.git (Jul 2021, #03; Tue, 13)

[Jeff King <peff@peff.net>]

On Mon, Jul 19, 2021 at 12:41:43PM +0200, Patrick Steinhardt wrote:

> > TBH, I had never really considered using TEST_OUTPUT_DIRECTORY for this
> > (--root predates it, and was written explicitly for the tmpfs case). But
> > I also think --root is more convenient:
> > 
> >   - "make test" will run in the tmpfs for speed, but "./t1234-foo.sh -i"
> >     will run locally, which makes it easy to "cd" in to inspect the
> >     result
> > 
> >   - likewise, I find accessing the results in t/test-results/*.out a
> >     little more convenient
> > 
> > But all of that is preference. I don't think you're wrong to use
> > TEST_OUTPUT_DIRECTORY this way, but the above points might be
> > interesting to you.
> 
> It is, thanks a lot for the hint. But given your first point about
> direct execution, this in fact makes me want TEST_OUTPUT_DIRECTORY in
> contrast to `--root=/path/to/tmpfs`: especially in the context of perf
> tests, I never run all of them together given that it takes such a long
> time. So I instead either run them directly or via the `./run` script,
> and in both cases I definitely want to have them in tmpfs given that
> there's a lot of disk churn if you're using biggish repos.

I generally use "./run", too. It will use GIT_TEST_OPTS under the hood
(which I actually find a little odd, just because it kicks in my usual
"-x --verbose-log", which I don't actually care about for the perf
tests).

You'd have to specify it manually for single-script runs, though. I
usually avoid single-script runs (and instead use "./run") because I try
to make sure each run is associated with a commit. Otherwise, it's easy
to confuse yourself about what the state of "this tree" was when it ran
(it does not even build fresh with GIT_PERF_MAKE_OPTS! So many times
I've accidentally tested a -O0 build from the current tree and wondered
why it was so slow).

-Peff