[openstack-dev] My failed attempt to speed up nova tests

Matthew Sherborne msherborne at gmail.com
Sat May 4 23:59:14 UTC 2013


So I tried to speed up the running of my test suite and failed.

I thought I'd share my experience in case someone else in the future
googles before
 trying the same thing, or in case some genius out there sees some fatal
flaw in my plan.

Here's what I did:

I'm on Ubuntu Raring. I have both gcc and clang compilers installed.

I did some experiments with a c++ test program and found that clang with
the -O3 optimization flag creates a faster program than gcc with -O6.

So I thought, I'll compile my own python and venv with python and clang and
-O3.

So I compiled my python from source with clang and -O3 and installed it in
~/python.

I deleted my venv for nova and, rebuilt it all under the new python.

Here are the *results* of: time ./run_tests.sh

*standard python:*

real    7m4.077s
user    21m0.080s
sys 0m24.596s

*with clang compiled python:*

real    8m11.396s
user    24m28.824s
sys 0m25.408s

I tried it a few times and got similar results. So it seems that the stock
ubuntu python is faster than my cmake -O3 compiled one.

All comments and suggestions welcomed.

Kind Regards,
Matthew Sherborne
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