NODES model#

The NODES runtime implements the OmpSs-2 tasking model, which schedules the execution of tasks with dependencies. It is designed to work on top of the nOS-V runtime while providing most of the functionalities from its predecessor, Nanos6.

The NODES library is instrumented to track the execution of tasks in each thread and also the execution path inside the library. The instrumentation traces are converted into Paraver views which are described in the following sections.

To enable the instrumentation of NODES on 1.4 or newer versions, add ovni.enabled = true to the nodes.toml configuration file. Older versions used the NODES_OVNI=1 environment variable. Follow the documentation for more details.

Subsystem view#

The subsystem view provides a simplified view on what NODES is doing over time. The view follows the same rules described in the subsystem view of Nanos6.

The complete list of states is shown below.

• Task subsystem: Controls the life cycle of tasks

  • Dependencies: Registering task accesses: Allocating and setting task access dependencies.

  • Dependencies: Unregistering task accesses: Deallocating task access dependencies. Can unblock other tasks.

  • If0: Waiting for an If0 task: Waiting for a task with the if(0) clause to finish.

  • If0: Executing an If0 task inline: Executing inline a task with the if(0) clause.

  • Taskwait: Taskwait: Waiting in a taskwait until dependencies are met.

  • Add Task: Creating a task: Allocates memory for a new task.

  • Add Task: Submitting a task: Places the task in the scheduler.

  • Spawn Function: Spawning a function: Creating a task by nanos6_spawn_function().