According to the James W. Smither and Manual London, authors of the book Performance Management, Putting Research into Action, Performance Management  serves 6 key purposes in an organization.
Putting a Performance Management System into place requires resources with focus on the organizational business goals and a hands on approach to implementation.  Knowing where to start is always one of the biggest challenges.  But starting is the first step to solid business results, engaged and motivated workforce and accountability overall.