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Clarify "Task: Running body" subsystem state

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Rodrigo Arias 2022-09-21 13:15:55 +02:00
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1 changed files with 20 additions and 9 deletions
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doc/emulation/nanos6.md
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@ -11,23 +11,27 @@ The library is instrumented to track the execution of tasks and also the
execution path inside the runtime library to identify what is happening. execution path inside the runtime library to identify what is happening.
This information is typically used by both the users and the developers This information is typically used by both the users and the developers
of the Nanos6 library to analyze problems and unwanted behaviors. of the Nanos6 library to analyze problems and unwanted behaviors.
Towards this goal, four different Paraver views are generated, which are Towards this goal, five different Paraver views are generated, which are
explained below. explained below.
The state of each task is modelled in a simple finite state machine, The state of each task is modelled in a simple finite state machine,
which identifies the main state changes of the task. The task is set to which identifies the main state changes of the task. The task is set to
the *Running* state only when is executing the body of the task, the *Running* state when it begins executing the body of the task,
consisting of user defined code. The states can be observed in the consisting of user defined code. The states can be observed in the
following diagram: following diagram:
![Nanos6 task states](fig/nanos6-task-model.svg) ![Nanos6 task states](fig/nanos6-task-model.svg)
A thread can only execute one task at a time, but multiple tasks can be
nested and only the topmost one will actually run. When a view presents
the running task of a thread, that one is always the top of the stack.
## Task ID view ## Task ID view
The task ID view represents the ID of the Nanos6 task instance that is The task ID view represents the numeric ID of the Nanos6 task that is
currently executing on each thread. This ID is a monotonically currently running on each thread. The ID is a monotonically increasing
increasing identifier assigned on task creation. Lower IDs correspond to identifier assigned on task creation. Lower IDs correspond to tasks
tasks created at an earlier point than higher IDs. created at an earlier point than higher IDs.
## Task type view ## Task type view
@ -38,8 +42,8 @@ in a program, every created task will have a different ID, but the same
type. type.
In the view, each type is shown with a label declared in the source with In the view, each type is shown with a label declared in the source with
the label attribute of the task. If no label was specified, one is the label attribute of the running task. If no label was specified, one
automatically generated for each type. is automatically generated for each type.
Note that in this view, the numeric event value is a hash function of Note that in this view, the numeric event value is a hash function of
the type label, so two distinct types (tasks declared in different parts the type label, so two distinct types (tasks declared in different parts
@ -111,7 +115,7 @@ The complete list of subsystems and sections is shown below.
- **Task subsystem**: Controls the life cycle of tasks - **Task subsystem**: Controls the life cycle of tasks
- **Body**: Executing the body of the task (user defined code). - **Running body**: Executing the body of the task (user defined code).
- **Spawning function**: Spawning a function as task that will be submitted - **Spawning function**: Spawning a function as task that will be submitted
for later execution. for later execution.
@ -178,3 +182,10 @@ The complete list of subsystems and sections is shown below.
- **Wait for deadline**: Blocking a deadline task, which will be - **Wait for deadline**: Blocking a deadline task, which will be
re-enqueued when a certain amount of time has passed re-enqueued when a certain amount of time has passed
!!! remark
Notice that tasks in the running state will display the "Task: Running
body" subsystem only when the task has not called any other instrumented
subsystem in Nanos6. Tasks will continue to be in the running state until
paused or finished.