[PATCH v1 0/4] Teach 'run' perf script to read config files

Goal ~~~~

Using many long environment variables to give parameters to the 'run' script is error prone and tiring.

We want to make it possible to store the parameters to the 'run' script in a config file. This will make it easier to store, reuse, share and compare parameters.

In the future it could also make it easy to run series of tests. 

Design ~~~~~~

We use the same config format as the ".git/config" file as Git users and developers are familiar with this nice format and have great tools to change, query and manage it.

We use values from the config file to set the environment variables that are used by the scripts if they are not already set.

Highlevel view of the patches in the series ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Patch 1/4 teaches the '--config <configfile>' option to the 'run' script, but <configfile> is just put into the GIT_PERF_CONFIG_FILE variable which is not used yet.

Patch 2/4 add the get_var_from_env_or_config() function to read config options from the <configfile> and set values to some variables from these config options or from default values.

Patch 3/4 and 4/4 use the get_var_from_env_or_config() function to make it possible to set parameters used by the 'run' script.

Future work ~~~~~~~~~~~

We want to make it possible to run series of tests by passing only a config file to the 'run' script.

For example a config file like the following could be used to run perf tests with Git compiled both with and without libpcre:

[perf]
        dirsOrRevs = v2.12.0 v2.13.0
        repeatCount = 10
[perf "with libpcre"]
        makeOpts = DEVELOPER=1 CFLAGS='-g -O0' USE_LIBPCRE=YesPlease
[perf "without libpcre"]
        makeOpts = DEVELOPER=1 CFLAGS='-g -O0'

This will make it easy to see what changes between the different runs.

But this can be added later, and the current series can already be useful as is.

Links ~~~~~

This patch series is also available here:

  https://github.com/chriscool/git/commits/perf-conf

Christian Couder (4):
  perf/run: add '--config' option to the 'run' script
  perf/run: add get_var_from_env_or_config()
  perf/run: add GIT_PERF_DIRS_OR_REVS
  perf/run: add calls to get_var_from_env_or_config()

 t/perf/perf-lib.sh |  3 ---
 t/perf/run         | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 4 deletions(-)