Apparatus and method for managing prefetch transactions

Abstract

An apparatus and method are provided for managing prefetch transactions. The apparatus has an interconnect for providing communication paths between elements coupled to the interconnect. The elements coupled to the interconnect comprise at least a requester element to initiate transactions, and a plurality of completer elements each of which is arranged to respond to a transaction received by that completer element. Congestion tracking circuitry maintains, in association with the requester element, a congestion indication for each of a plurality of routes through the interconnect used to propagate transactions initiated by that requester element. Each route comprises one or more communication paths, and the route employed to propagate a given transaction is dependent on a target completer element for that transaction. Prefetch throttling circuitry then identifies, in response to an indication of a given prefetch transaction that the requester element wishes to initiate, the target completer element amongst the plurality of completer elements to which that given prefetch transaction would be issued. It then determines whether to issue the given prefetch transaction in dependence on the congestion indication for the route that has been determined.