[Python-Dev] Possible performance regression

[Eric Snow]

On Mon, Feb 25, 2019 at 10:42 AM Eric Snow <ericsnowcurrently at gmail.com> wrote:
> I'll look into it around then too.  See https://bugs.python.org/issue33608.

I ran the "performance" suite (https://github.com/python/performance),
which has 57 different benchmarks.  In the results, 9 were marked as
"significantly" different between the two commits..  2 of the
benchmarks showed a marginal slowdown and 7 showed a marginal speedup:

+-------------------------+--------------+-------------+--------------+-----------------------+
| Benchmark               | speed.before | speed.after | Change
| Significance          |
+=========================+==============+=============+==============+=======================+
| django_template         | 177 ms       | 172 ms      | 1.03x faster
| Significant (t=3.66)  |
+-------------------------+--------------+-------------+--------------+-----------------------+
| html5lib                | 126 ms       | 122 ms      | 1.03x faster
| Significant (t=3.46)  |
+-------------------------+--------------+-------------+--------------+-----------------------+
| json_dumps              | 17.6 ms      | 17.2 ms     | 1.02x faster
| Significant (t=2.65)  |
+-------------------------+--------------+-------------+--------------+-----------------------+
| nbody                   | 157 ms       | 161 ms      | 1.03x slower
| Significant (t=-3.85) |
+-------------------------+--------------+-------------+--------------+-----------------------+
| pickle_dict             | 29.5 us      | 30.5 us     | 1.03x slower
| Significant (t=-6.37) |
+-------------------------+--------------+-------------+--------------+-----------------------+
| scimark_monte_carlo     | 144 ms       | 139 ms      | 1.04x faster
| Significant (t=3.61)  |
+-------------------------+--------------+-------------+--------------+-----------------------+
| scimark_sparse_mat_mult | 5.41 ms      | 5.25 ms     | 1.03x faster
| Significant (t=4.26)  |
+-------------------------+--------------+-------------+--------------+-----------------------+
| sqlite_synth            | 3.99 us      | 3.91 us     | 1.02x faster
| Significant (t=2.49)  |
+-------------------------+--------------+-------------+--------------+-----------------------+
| unpickle_pure_python    | 497 us       | 481 us      | 1.03x faster
| Significant (t=5.04)  |
+-------------------------+--------------+-------------+--------------+-----------------------+

  (Issue #33608 has more detail.)

So it looks like commit ef4ac967 is not responsible for a performance
regression.

-eric