Preemptive operating system without context switching

• US 9,280,389 B1
• Filed: 12/30/2014
• Issued: 03/08/2016
• Est. Priority Date: 12/30/2014
• Status: Active Grant

• Current Assignee: Tyco Fire & Security GmbH (Johnson Controls International plc)
• Original Assignee: Tyco Fire & Security GmbH (Johnson Controls International plc)
• Inventors: Lipsio, Vincent J. Jr., Rasband, Paul B.
• Primary Examiner(s): Rampuria, Satish
• Application Number:
  US14/585,353
• Time in Patent Office: 434 Days
• Field of Search: 718101-108
• US Class Current: 1/1
• CPC Class Codes: G06F 9/461 Saving or restoring of program or task context
• CPC Class Codes: G06F 9/4812 by interrupt, e.g. masked
• CPC Class Codes: G06F 9/4843 by program, e.g. task dispatcher, supervisor, operating system
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues

Abstract

A device, such as a constrained device that includes a processing device and memory, schedules user-defined independently executable functions to execute from a single stack common to all user-defined independently executable functions according to availability and priority of the user-defined independently executable functions relative to other user-defined independently executable functions and preempts currently running user-defined independently executable function by placing the particular user-defined independently executable function on a single stack that has register values for the currently running user-defined independently executable function.

Claims

1. A computer program product tangibly stored on a computer readable hardware storage device, the computer program product for managing constrained computing devices, the computer program product comprising instructions to cause a processor to:

schedule user-defined independently executable functions to execute from a single stack common to all user-defined independently executable functions by the processor according to availability and priority of the user-defined independently executable functions relative to other user-defined independently executable functions, with the instructions to schedule further causing the processor to;

identify a particular user-defined independently executable function as ready to run, which user-defined independently executable functions is of higher priority than a user-defined independently executable function currently running;

execute a direct call to a wrap function that wraps the particular user-defined independently executable function;

preempt the currently running user-defined independently executable function by the instructions placing the particular wrapped user-defined independently executable function on the single stack that has register values for the currently running user-defined independently executable function, pushing down the state data of the currently running user-defined independently executable function lower in the stack;

execute the particular user-defined independently executable function; and

pop from the stack those register values of the particular user-defined independently executable function, after execution of the particular user-defined independently executable function.

2. The computer program product of claim 1 wherein the computer program product is part of a real-time operating system for execution on a constrained device.

3. The computer program product of claim 1 wherein the a wrapper function for the particular user-defined independently executable function is used with an interrupt service routine identifying the particular user-defined function as ready to run.

4. The computer program product of claim 3 wherein the schedule instructions invoke preemption by the interrupt service routine and by instructions to mark the currently running user-defined independently executable function for execution upon return from the interrupt, and with the wrapper function being a subroutine in a software library or a computer program that calls a method to handle the interrupt service routine.

5. The computer program product of claim 1 wherein the stack saves register values for all user-defined independently executable functions, interrupt service routines, and operating system routines.

6. The computer program product of claim 1 wherein saved register values, for any preempted user-defined independently executable functions, interrupt service routines, and operating system routines, are saved on the stack using code generated by a compiler.

7. The computer program product of claim 1 further comprising instructions to:

restore the state data of the currently running user-defined independently executable function in the stack when the particular user-defined function completes running.

8. A method executed in a computing system that comprises processor and memory, the method comprising:

scheduling by a processor in the computing systems, user-defined independently executable functions to execute from a single stack common to all user-defined independently executable functions according to availability and priority of the user-defined independently executable functions relative to other user-defined independently executable functions;

identifying by the processor a particular user-defined independently executable function as ready to run, which user-defined independently executable functions is of higher priority than a user-defined independently executable function currently running;

directly calling a wrapper function that wraps the particular user-defined independently executable function;

preempting by the processor, the currently running user-defined independently executable function by placing the particular wrapped user-defined independently executable function on the single stack that has register values for the currently running user-defined independently executable function, pushing down the state data of the currently running user-defined independently executable function lower in the stack;

executing by the processor the particular user-defined independently executable function; and

pushing up by the processor in the stack those register values of the current running user-defined independently executable function, after execution of the particular user-defined independently executable function.

9. The method of claim 8 wherein the method executes in a real-time operating system environment on a constrained device.

10. The method of claim 8 wherein the calling a wrapper function for the particular user-defined independently executable function is used with an interrupt service routine that identifies the particular user-defined function as ready to run.

11. The method of claim 10 wherein scheduling further comprises:

invoking preemption by the interrupt service routine to mark a currently running user-defined independently executable function for execution upon return from the interrupt, and with the wrapper function being a subroutine in a software library or a computer program that calls a method to handle the interrupt service routine.

12. The method of claim 8 wherein the stack saves register values for all user-defined independently executable functions, interrupt service routines, and operating system routines.

13. The method of claim 12 wherein saved register values for any preempted user-defined independently executable functions, interrupt service routines, and operating system routines are saved on the stack using code generated by a compiler.

14. The method of claim 13 further comprising:

restoring the state data of the currently running user-defined independently executable function in the stack when the particular user-defined function completes running.

15. A constrained device comprises:

a processor device, configured to;

schedule by the processor user-defined independently executable functions to execute from a single stack common to all user-defined independently executable functions according to availability and priority of the user-defined independently executable functions relative to others of the user-defined independently executable functions, with the processor further configured to;

identify a particular user-defined independently executable function as ready to run, which user-defined independently executable functions is of higher priority than a user-defined independently executable function currently running;

directly call a wrapper function that wraps the particular user-defined independently executable function;

preempt the currently running user-defined independently executable function by the instructions placing the particular wrapped user-defined independently executable function on the single stack that has register values for the currently running user-defined independently executable function, pushing down the state data of the currently running user-defined independently executable function lower in the stack;

execute the particular user-defined independently executable function; and

pop from the stack those register values of the particular user-defined independently executable function, after execution of the particular user-defined independently executable function.

16. The device of claim 15 further comprising:

a sensor element for sensing a physical condition, the sensor element sending data for processing to the processing device, with the processing device applying one or more user-defined independently executable functions to the data.

17. The device of claim 15 further comprising:

a network interface to interface the device to a network.

18. The device of claim 15 further comprising:

a storage device storing a computer program product comprising instructions to configure the processor device to schedule the user-defined independently executable functions to execute.

19. The device of claim 15 wherein the constrained device operates using a real-time operating system and the calling a wrapper function for the particular user-defined independently executable function is used with an interrupt service routine that identifies the particular user-defined function as ready to run.

20. The device of claim 15 wherein the wrapper function for the particular user-defined independently executable function is used with an interrupt service routine identifying the particular user-defined function and with the wrapper function being a subroutine in a software library or a computer program that calls a method to handle the interrupt service routine.