Analyze and optimize crontabs [closed]
Solution 1:
The only thing I've done is move cron jobs into a structured job scheduler in order to graph dependencies and gain visibility into the effects downtime windows.
Solution 2:
Sounds like this is the functionality you'd like http://www.phpclasses.org/package/6673-PHP-Parse-crontab-schedule-and-generate-Gantt-charts.html
I can't vouch for the above, it is just the results of some web searching.