1. A method of managing per-virtual port performance metrics in a logically partitioned data processing system, the method comprising the computer implemented steps of: receiving a request to perform a management operation for a particular virtual port; determining by a physical adapter whether the management operation is a read of metrics for the particular virtual port; responsive to determining that the management operation is not a read, determining by the physical adapter whether the management operation is an initialize operation of the metrics for the particular virtual port; responsive to determining that the management operation is an initialize operation, determining whether the particular virtual port is an upstream port or a downstream port; responsive to determining that the particular virtual port is an upstream port, allocating by the physical adapter an upstream virtual port table for the particular virtual port; responsive to determining that the particular virtual port is a downstream port, allocating by the physical adapter a downstream virtual port table for the particular virtual port; assigning the allocated virtual port table to the particular virtual port; resetting the metrics for the particular virtual port to zero in the virtual port table that was allocated for the particular virtual port; and transferring completion results to a host through a direct memory access operation; responsive to determining that the management operation is not an initialize operation, determining whether the management operation is a destroy operation; responsive to determining that the management operation is a destroy operation, destroying the virtual port table for the particular virtual port; and responsive to determining that the management operation is not a destroy operation, resetting the metrics for the particular virtual port to zero in the virtual port table that was allocated for the particular virtual port.