A data processing system 20 comprising an accelerator 12 that acts as a common shared resource for plural applications 3 executing in respective virtual machines 4, 5. The data processing system 20 includes an interface mapping unit 21 that facilitates the submission of tasks from applications to the accelerator 12. The interface mapping unit 21 includes physical registers 8 that act as physical register input/output interfaces for the accelerator 12. The interface mapping unit 21 exposes a plurality of virtual accelerator input/output interfaces 22 to the applications 3 that are then dynamically mapped to the physical register input/output interfaces 8 by the interface mapping unit 21 to allow applications to access, and thereby submit a task to, a given physical register input/output interface 8.