Common scheduling and synchronization primitives

• US 9,128,736 B1
• Filed: 02/20/2013
• Issued: 09/08/2015
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: McCann, Peter J., Gould, Christopher M., Brown, Jeffrey A.
• Primary Examiner(s): Sough, H S
• Assistant Examiner(s): Yun, Carina
• Application Number:
  US13/771,268
• Time in Patent Office: 930 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 9/445 Program loading or initiating bootstrapping G06F9/4401; security arrangements for program loading or initiating G06F21/57
• CPC Class Codes: G06F 9/4812 by interrupt, e.g. masked
• CPC Class Codes: G06F 9/4825 Interrupt from clock, e.g. time of day
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: G06F 9/545 where tasks reside in different layers, e.g. user- and kernel-space

Abstract

Described are techniques for executing code performing one or more operations corresponding to scheduling and synchronization primitives. During execution of the code, a call is performed using an application programming interface requesting a first of the operations corresponding to one of said scheduling and synchronization primitives. During runtime in response to said call, it is determined whether to perform the first operation. The determining step uses a set of one or more criteria indicating conditions as to when the scheduling and synchronization primitives are allowed to be performed. The one or more criteria are determined in accordance with a plurality of different platforms. If it is determined that the first operation is allowable and the first operation is to be performed, then the code can be executed on each of the different platforms in a privileged execution mode and a non-privileged execution mode.

Claims

1. A method of executing code, the method comprising:

performing, by said code during execution of said code, a call using an application programming interface requesting a first of a plurality of operations, said plurality of operations corresponding to scheduling and synchronization primitives which are operations performed on different scheduling objects;

determining, during runtime in response to said call, whether to perform said first operation, said determining using a set of one or more criteria indicating conditions as to when said scheduling and synchronization primitives are allowed to be performed, said one or more criteria being determined in accordance with a plurality of different platforms, wherein said plurality of operations are performed in accordance with a set of semantics specified using the set of one or more criteria whereby each of said plurality of operations, when executed in accordance with said set of one or more criteria, exhibits a same runtime behavior when executed in a privileged execution mode and a non-privileged execution mode on each of said different platforms; and

invoking code of the application programming interface to register a device driver executing in the non-privileged execution mode and including an interrupt service routine that services interrupts for a device and executes in the non-privileged execution mode, wherein a reader-writer lock is used by code that executes in the non-privileged execution mode to implement disabling and enabling interrupts in accordance with semantics of the privileged execution mode, wherein one or more readers are allowed read access to the read-write lock when not already accessed for writing and wherein a writer with write access to the read-write lock has exclusive access to the read-write lock.

2. The method of claim 1, wherein the different scheduling objects include at least one object having operations performed thereon in accordance with kernel-mode semantics and code of the application programming interface simulates said at least one object and operations performed thereon in accordance with the kernel-mode semantics in connection with code that executes in said non-privileged execution mode.

3. The method of claim 1, wherein the plurality of different platforms includes a first platform having a first operating system and a second platform having a second operating system different from the first operating system, and wherein said plurality of operations performed on different scheduling objects exhibit the same runtime behavior when executed in the privileged execution mode and the non-privileged execution mode on the first platform and the second platform.

4. The method of claim 1, wherein the plurality of different platforms includes a first platform including first hardware and a second platform including second hardware having a processor architecture different from the first hardware, and wherein said plurality of operations performed on different scheduling objects exhibit the same runtime behavior when executed in the privileged execution mode and the non-privileged execution mode on the first platform and the second platform.

5. The method of claim 1, wherein first code of the application programming interface simulates functionality in connection with a deferred procedure call executed in the non-privileged mode using threads.

6. The method of claim 1, wherein first code of the application programming interface simulates functionality in connection with an interrupt service routine executed in the non-privileged mode using threads.

7. The method of claim 1, wherein said conditions indicate allowable execution contexts using an execution level and a spin lock held indicator, said execution level indicating a runtime execution context level associated with said other code at a current execution point, said spin lock held indicator providing a runtime indication as to whether a spin lock is currently acquired at said current execution point.

8. The method of claim 7, wherein said execution level is set to one of a plurality of execution level values, said plurality of execution level values including a thread level, a deferred procedure call level and an interrupt level, said thread level indicating that said current execution point corresponds to a body of code associated with a thread or a deferred work item, said deferred procedure call level indicating that said current execution point corresponds to a body of code associated with a deferred procedure call or a timer, and said interrupt level indicating that said current execution point corresponds to a body of code associated with an interrupt service routine.

9. The method of claim 8, wherein said code includes a first call using said application programming interface to perform one of said plurality of operations in connection with said scheduling objects including any of a mutual exclusion lock, a spin lock, a condition variable, a semaphore, and an event, and said application programming interface provides an interface to instantiate an object corresponding to a thread, a deferred procedure call, or an interrupt service routine.

10. The method of claim 7, further comprising:

updating said execution level and said spin lock held indicator during execution of said code to reflect a current runtime execution state of said code.

11. The method of claim 7, wherein said execution level and said spin lock held indicator are examined prior to performing said first operation to determine whether to perform said first operation.

12. The method of claim 1, wherein said application programming interface provides an interface to a code module that performs said one or more operations when said code executes in a non-privileged that is user mode, and performs said one or more operations when said code executes in a privileged mode that is kernel mode.

13. The method of claim 1, wherein said application programming interface includes one or more methods which perform said operations on said objects.

14. The method of claim 1, wherein when one or more readers are accessing the reader-writer lock, interrupts are disabled and when there is no reader accessing the reader-writer lock, interrupts are enabled.

15. The method of claim 1, wherein, upon an occurrence of an interrupt for the device, the interrupt service routine executing in the non-privileged execution mode is invoked using another interrupt service routine that executes in the privileged execution mode.

16. A non-transitory computer readable medium comprising code stored thereon, wherein the code, when executed, performs a method comprising:

providing an application programming interface for performing a plurality of operations, said plurality of operations corresponding to scheduling and synchronization primitives which are operations performed on different scheduling objects;

providing a set of one or more criteria indicating conditions as to when said scheduling and synchronization primitives are allowed to be performed, said one or more criteria being determined in accordance with a plurality of different platforms;

performing, by other code during execution of other code, a call using said application programming interface to perform a first one of the plurality of operations;

determining, during runtime in response to said call and using said set of one or more criteria, whether to perform said first operation, wherein said plurality of operations are performed in accordance with a set of semantics specified using the set of one or more criteria whereby each of said plurality of operations, when executed in accordance with said set of one or more criteria, exhibits a same runtime behavior when executed in a privileged execution mode and a non-privileged execution mode on each of said different platforms; and

invoking code of the application programming interface to register a device driver executing in the non-privileged execution mode and including an interrupt service routine that services interrupts for a device and executes in the non-privileged execution mode, wherein a reader-writer lock is used by code that executes in the non-privileged execution mode to implement disabling and enabling interrupts in accordance with semantics of the privileged execution mode, wherein one or more readers are allowed read access to the read-write lock when not already accessed for writing and wherein a writer with write access to the read-write lock has exclusive access to the read-write lock.

17. The non-transitory computer readable medium of claim 16, wherein the different scheduling objects includes at least one object having operations performed thereon in accordance with kernel-mode semantics and code of the application programming interface simulates said at least one object and operations performed thereon in accordance with the kernel-mode semantics in connection with code that executes in said non-privileged execution mode.

18. The non-transitory computer readable medium of claim 16, wherein the plurality of different platforms includes a first platform having a first operating system and a second platform having a second operating system different from the first operating, system, and wherein said plurality of operations performed on different scheduling objects exhibit the same runtime behavior when executed in the privileged execution mode and the non-privileged execution mode on the first platform and the second platform.

19. The non-transitory computer readable medium of claim 16, wherein the plurality of different platforms includes a first platform including first hardware and a second platform including second hardware having a processor architecture different from the first hardware, and wherein said plurality of operations performed on different scheduling objects exhibit the same runtime behavior when executed in the privileged execution mode and the non-privileged execution mode on the first platform and the second platform.

20. The non-transitory computer readable medium of claim 16, wherein first code of the application programming interface simulates functionality in connection with a deferred procedure call executed in the non-privileged mode using threads.

21. The non-transitory computer readable medium of claim 16, wherein first code of the application programming interface simulates functionality in connection with an interrupt service routine executed in the non-privileged mode using threads.