[Python-Dev] Help requested with Python 2.7 performance regression

[Louis Bouchard]

Hello,

Le 03/03/2017 à 08:27, Nick Coghlan a écrit :
> On 2 March 2017 at 07:00, Victor Stinner <victor.stinner at gmail.com
> <mailto:victor.stinner at gmail.com>> wrote:
> 
>     Hi,
> 
>     Your document doesn't explain how you configured the host to run
>     benchmarks. Maybe you didn't tune Linux or anything else? Be careful
>     with modern hardware which can make funny (or not) surprises.
> 
> 
> Victor, do you know if you or anyone else has compared the RHEL/CentOS 7.x
> binaries (Python 2.7.5 + patches, built with GCC 4.8.x) with the Fedora 25
> binaries (Python 2.7.13 + patches, built with GCC 6.3.x)?
> 
> I know you've been using perf to look for differences between *Python* major
> versions, but this would be more about using Python's benchmark suite to
> investigate the performance of *gcc*, since it appears that may be the culprit here.
> 
> Cheers,
> Nick.

Out of curiosity, I ran the set of benchmarks in two LXC containers running
centos7 (2.7.5 + gcc 4.8.5) and Fedora 25 (2.7.13 + gcc 6.3.x). The benchmarks
do run faster in 18 benchmarks, slower on 12 and insignificant for the rest (~33
from memory).

Do take into account that this is run on baremetal system running an Ubuntu
kernel (4.4.0-59) so this is by no mean a reference value but just for a quick
test. Results were appended to the spreadsheet referred to in the analysis document.

It is somewhat coherent with a previous test I ran where I disabled PGO on
2.7.6+gcc4.8 (Trusty). This made the 2.7.6+gcc4.8 (Trusty) interpreter to become
slower than the Xenial reference.

Unfortunately, I cannot redeploy my server on RHEL or Fedora at the moment so
this is as far as I can go.

Kind regards,

...Louis


-- 
Louis Bouchard
Software engineer, Cloud & Sustaining eng.
Canonical Ltd
Ubuntu developer                       Debian Maintainer
GPG : 429D 7A3B DD05 B6F8 AF63  B9C4 8B3D 867C 823E 7A61