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D.12 Other Optimizations and Determinism Rules

1
This clause describes various requirements for improving the response and determinism in a real-time system. 

Implementation Requirements

2
If the implementation blocks interrupts (see C.3) not as a result of direct user action (e.g. an execution of a protected action) there shall be an upper bound on the duration of this blocking.
3
The implementation shall recognize entry-less protected types. The overhead of acquiring the execution resource of an object of such a type (see 9.5.1) shall be minimized. In particular, there should not be any overhead due to evaluating entry_barrier conditions.
4
Unchecked_Deallocation shall be supported for terminated tasks that are designated by access types, and shall have the effect of releasing all the storage associated with the task. This includes any run-time system or heap storage that has been implicitly allocated for the task by the implementation.

Documentation Requirements

5
The implementation shall document the upper bound on the duration of interrupt blocking caused by the implementation. If this is different for different interrupts or interrupt priority levels, it should be documented for each case. 

Metrics

6
The implementation shall document the following metric: 
7
8
9
protected Lock is
   procedure Set;
   function Read return Boolean;
private
   Flag : Boolean := False;
end Lock;
10
protected body Lock is
   procedure Set is
   begin
      Flag := True;
   end Set;
   function Read return Boolean
   Begin
      return Flag;
   end Read;
end Lock;
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