Level Zero

The oneAPI Level Zero (Level Zero) provides low-level direct-to-metal interfaces that are tailored to the devices in a oneAPI platform. Level Zero supports broader language features such as function pointers, virtual functions, unified memory, and I/O capabilities while also providing fine-grain explicit controls needed by higher-level runtime APIs including:

  • Device discovery

  • Memory allocation

  • Peer-to-peer communication

  • Inter-process sharing

  • Kernel submission

  • Asynchronous execution and scheduling

  • Synchronization primitives

  • Metrics reporting

The API architecture exposes both physical and logical abstractions of the underlying oneAPI platform devices and their capabilities. The device, sub-device, and memory are exposed at a physical level while command queues, events, and synchronization methods are defined as logical entities. All logical entities are bound to device-level physical capabilities. The API provides a scheduling model that is tailored to multiple uses including a low-latency submission model to the devices as well as one that is tailored to the construction and submission of work across simultaneous host threads. While heavily influenced by other low-level APIs, such as OpenCL, Level Zero is designed to evolve independently. While heavily influenced by GPU architecture, Level Zero is supportable across different oneAPI compute device architectures, such as FPGAs.

Detailed API Descriptions

The detailed specification can be found online in the specification.