Method for arbitration and access to hardware request ring structures in a concurrent environment

Abstract

Methods and apparatus for arbitration and access to hardware request ring structures in a concurrent environment. A request ring mechanism is provided including an arbiter, ring overflow guard, request ring, and request ring metadata, each of which is implemented in shared virtual memory (SVM) on a computing platform including a multi-core processor coupled to an offload device having one or more SVM-capable accelerators. Worker threads request to access the request ring to provide job descriptors to be processed by the accelerator(s). A lockless arbiter returns either an index of a slot in which to write a descriptor or information indicating the ring is full to each worker thread. The scheme enables worker threads to write descriptors to slots in the request ring corresponding to the returned indexes without contention from other worker threads. The ring overflow guard prevents valid descriptors from being overwritten before they are taken off the ring by the accelerator(s). The request ring metadata is used indicate a valid/invalid status of the ring entries.