1. A method for offloading a data transfer statistic from a packet forwarding engine (PFE) forming part of a forwarding unit in a mobile access gateway, the method comprising: receiving, at the forwarding unit of the mobile access gateway, packets associated with a subscriber session for a subscriber; updating, by the PFE, the data transfer statistic based on quantities of data in the received packets, the data transfer statistic stored in a memory within the PFE; generating, by the mobile access gateway, synthetic packets, the synthetic packets having a packet type different than packet types of any packets received by the forwarding unit from a content access network or a packet data network; and responsive to determining a packet is a synthetic packet, performing, by the PFE, a callout operation to push the data transfer statistic from the memory of the PFE to a memory of the forwarding unit, the memory of the forwarding unit being separate from the memory within the PFE.