Assume that you install a SQL Server 2014 Reporting Services report server as a named instance. After you install Cumulative Update 6 (CU6) for SQL Server 2014 Service Pack 1 (SP1), the performance counter object ReportServer$instance_name:Service is missing from Windows Performance Monitor.
This problem was first fixed in the following cumulative update for SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server: