# nOS-V model

The nOS-V runtime is composed of tasks that can be scheduled to run in
threads. Tasks can be paused and resumed, leaving the CPUs free to
execute other tasks. The nOS-V model tracks the state of each task as
well as the state of the runtime internal state.

## Task type colors

In the Paraver timeline, the color assigned to each nOS-V task type is
computed from the task type label using a hash function; the task type
id doesn't affect in any way how the color gets assigned. This method
provides two desirable properties:

- Invariant type colors over time: the order in which task types are
  created doesn't affect their color.

- Deterministic colors among threads: task types with the same label end
  up mapped to the same color, even if they are from different threads
  located in different nodes.

For more details, see [this MR][1].

[1]: https://pm.bsc.es/gitlab/rarias/ovni/-/merge_requests/27

## Subsystem view

The subsystem view provides a simplified view on what is the nOS-V
runtime doing over time. The view follows the same rules described in
the [subsystem view of Nanos6](../nanos6/#subsystem_view).