Samsung S5PC110 Manual page 427

S5PC110_UM
5.2.2.1 Handling System Events
When an event occurs that might influence the optimum performance level, the OS calls the appropriate kernel
hook in the IEM kernel:
•
The New Task hook is called whenever a new task is created. This hook generates a New Task system event
for the new task that has just been created.
•
The Exit hook is called whenever a task is about to exit. This hook generates a Task Exit system event for the
exiting task.
•
The Task Switch hook is called whenever the OS switches from one task to another. This hook generates two
system events:
−
A Task Schedule Out system event for the previous task that has just been switched out
−
A Task Schedule In system event for the next task that is being switched in.
•
The User Input hook is called whenever a task receives user input. This hook generates a User Input system
event for the task that is receiving input.
When a kernel hook generates an system event, it determines whether any event handlers recognize the system
event. If so, it:
•
Creates a structure describing the system event
•
Ensures that there is an IEM block describing the corresponding task
•
Runs the fast event handlers to process the system event.
The kernel hook then determines whether any standard event handlers recognize the system event. If so, the
kernel hook adds the event to the event queue, for subsequent processing by the standard event handlers.
The kernel hook finally ensures that, if there are any system events in the event queue, the standard event
handlers run within a given period.
5 INTELLIGENT ENERGY MANAGEMENT
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