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

[Christian Couder <christian.couder@gmail.com>]

On Fri, Jul 14, 2017 at 8:27 AM, Christian Couder
<christian.couder@gmail.com> wrote:
> On Thu, Jul 13, 2017 at 10:55 PM, Jeff King <peff@peff.net> wrote:
>> On Thu, Jul 13, 2017 at 08:57:01PM +0200, Christian Couder wrote:
>>
>>> >> 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.
>>> >
>>> > Because perf-lib is built on test-lib, it already reads
>>> > GIT-BUILD-OPTIONS.
>>>
>>> Actually the 'run' script also sources GIT-BUILD-OPTIONS, so maybe
>>> this is not necessary.
>>
>> Ah, right. The one that comes via perf-lib gets the variables into the
>> test scripts themselves. But anything "run" would need itself would come
>> from the source it does itself. And that's where GIT_PERF_MAKE_OPTS has
>> an effect.
>>
>>> Also are the variables in GIT-BUILD-OPTIONS exported already?
>>
>> No, I don't think so. But because both "run" and the scripts themselves
>> source them, they're available more or less everywhere, except for
>> sub-processes inside the scripts.
>
> Ok, I see.

Actually after taking another look at that, it looks like the following happens:

1) the run script sources the original GIT-BUILD-OPTIONS file from
../.. relative to its location
2) a git version is built in "build/$rev" using GIT_PERF_MAKE_OPTS
which generates a new GIT-BUILD-OPTIONS file in "build/$rev/"
3) when the actual perf scripts are run they source the original
GIT-BUILD-OPTIONS file (through perf-lib.sh which sources test-lib.sh)

I wonder how useful 1) is, as the variables sourced from original
GIT-BUILD-OPTIONS are not used inside the "run" script and not
available to its child processes as they are not exported.
Is it just so that if people add GIT_PERF_* variables to their
config.mak before building they can then have those variables used by
the run script?

I also wonder if it would be better at step 3) to source the
GIT-BUILD-OPTIONS file generated at step 2) instead of the original
one, because they can be different as the options in
$GIT_PERF_MAKE_OPTS will be baked into the new GIT-BUILD-OPTIONS file.
(Of course if $GIT_PERF_MAKE_OPTS was added to config.mak before
building, then they will be in the original one too. But
$GIT_PERF_MAKE_OPTS should work without that.)