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D.13 The Ravenscar and Jorvik Profiles

1
2/5
This subclause defines the Ravenscar and Jorvik profiles. 
Paragraphs 2 and 3 were moved to 13.12, “Pragma Restrictions and Pragma Profile”. 

Legality Rules

5/3
The profile_identifier Ravenscar and profile_identifier Jorvik are usage profiles (see 13.12). For usage profiles Ravenscar and Jorvik, there shall be no profile_pragma_argument_associations.

Static Semantics

6/3
The usage profile Ravenscar is equivalent to the following set of pragmas:
7/4
pragma Task_Dispatching_Policy (FIFO_Within_Priorities);
pragma Locking_Policy (Ceiling_Locking);
pragma Detect_Blocking;
pragma Restrictions (
              No_Abort_Statements,
              No_Dynamic_Attachment,
              No_Dynamic_CPU_Assignment,
              No_Dynamic_Priorities,
              No_Implicit_Heap_Allocations,
              No_Local_Protected_Objects,
              No_Local_Timing_Events,
              No_Protected_Type_Allocators,
              No_Relative_Delay,
              No_Requeue_Statements,
              No_Select_Statements,
              No_Specific_Termination_Handlers,
              No_Task_Allocators,
              No_Task_Hierarchy,
              No_Task_Termination,
              Simple_Barriers,
              Max_Entry_Queue_Length => 1,
              Max_Protected_Entries => 1,
              Max_Task_Entries => 0,
              No_Dependence => Ada.Asynchronous_Task_Control,
              No_Dependence => Ada.Calendar,
              No_Dependence => Ada.Execution_Time.Group_Budgets,
              No_Dependence => Ada.Execution_Time.Timers,
              No_Dependence => Ada.Synchronous_Barriers,
              No_Dependence => Ada.Task_Attributes,
              No_Dependence => System.Multiprocessors.Dispatching_Domains);
7.1/5
 The usage profile Jorvik is equivalent to the following set of pragmas:
7.2/5
pragma Task_Dispatching_Policy (FIFO_Within_Priorities);
pragma Locking_Policy (Ceiling_Locking);
pragma Detect_Blocking;
pragma Restrictions (
              No_Abort_Statements,
              No_Dynamic_Attachment,
              No_Dynamic_CPU_Assignment,
              No_Dynamic_Priorities,
              No_Local_Protected_Objects,
              No_Local_Timing_Events,
              No_Protected_Type_Allocators,
              No_Requeue_Statements,
              No_Select_Statements,
              No_Specific_Termination_Handlers,
              No_Task_Allocators,
              No_Task_Hierarchy,
              No_Task_Termination,
              Pure_Barriers,
              Max_Task_Entries => 0,
              No_Dependence => Ada.Asynchronous_Task_Control,
              No_Dependence => Ada.Execution_Time.Group_Budgets,
              No_Dependence => Ada.Execution_Time.Timers,
              No_Dependence => Ada.Task_Attributes,
              No_Dependence => System.Multiprocessors.Dispatching_Domains);
Paragraph 7 was deleted.

Implementation Requirements

9/4
This paragraph was deleted.

Implementation Advice

10/5
On a multiprocessor system, an implementation should support a fully partitioned approach if one of these profiles is specified. Each processor should have separate and disjoint ready queues.
NOTES
11/5
41  For the Ravenscar profile, the effect of the restriction Max_Entry_Queue_Length => 1 applies only to protected entry queues due to the accompanying restriction Max_Task_Entries => 0. The restriction Max_Entry_Queue_Length is not applied by the Jorvik profile.
12/5
42  When the Ravenscar or Jorvik profile is in effect (via the effect of the No_Dynamic_CPU_Assignment restriction), all of the tasks in the partition will execute on a single CPU unless the programmer explicitly uses aspect CPU to specify the CPU assignments for tasks. The use of multiple CPUs requires care, as many guarantees of single CPU scheduling no longer apply.
13/5
43  It is not recommended to specify the CPU of a task to be Not_A_Specific_CPU when the Ravenscar or Jorvik profile is in effect. How a partition executes strongly depends on the assignment of tasks to CPUs.
14/5
44  Any unit that meets the requirements of the Ravenscar profile also meets the requirements of the Yorvik profile.

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