What is the difference between a free forecast and a cycled model run? This GFS wiki mentions both, but does not define them.
Cool, didn't realize that the GFS was on Github.
Looking on down the wiki, it seems like the "free-forecast" is associated with the deterministic model, while the "cycled" is associated with the Ensemble Kalman Filter. That is, the free-forecast is not constrained by data assimilation algorithms- it can just start from a restart file and go. A cycled run, however, needs multiple runs, as well as data.
This is all speculation based on naming conventions. If you really want an answer, perhaps asking the code developer?