`perflogs` not created when using `sn.make_performance_function`

[jack-morrison]

I'm opening this issue following this discussion in the ReFrame Slack.

After migrating to 4.x, I find that my test's exclusive use of sn.make_performance_function (no use of the @performance_function decorator) causes the perflogs directory not to be created, and yields no performance log files following the successful run of a performance test.

[vkarak]

I can confirm this behaviour; it's certainly a bug.

[vkarak]

At the moment, you can workaround this if you don't set the perf_variables in pre-performance hook, but rather in an after sanity hook. The reason is that reframe checks if a test is a performance test and enables the performance logger just before it enters the performance stage. If you set the perf_variables during the performance stage (the logical thing), at the moment of the check, they are still empty and reframe would think that this is not a performance test. Another workaround would be to fill perf_variables with some dummy data at the beginning.

[vkarak]

Merged into develop.