Symmetric Multi-Processor System

• US 20110289511A1
• Filed: 08/04/2011
• Published: 11/24/2011
• Est. Priority Date: 08/25/1999
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: QNX Software Systems Company (Blackberry Limited)
• Inventors: van der Veen, Peter
• Granted Patent: US 8,572,626 B2
• Time in Patent Office: Days
• US Class Current: 718/106
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

The present invention relates generally to computer operating systems, and more specifically, to operating system calls in a symmetric multiprocessing (SMP) environment. Existing SMP strategies either use a single lock or multiple locks to limit access to critical areas of the operating system to one thread at a time. These strategies suffer from a number of performance problems including slow execution, large software and execution overheads and deadlocking problems. The invention applies a single lock strategy to a micro kernel operating system design which delegates functionality to external processes. The micro kernel has a single critical area, the micro kernel itself, which executes very quickly, while the external processes are protected by proper thread management. As a result, a single lock may be used, overcoming the performance problems of the existing strategies.

Claims

1. A method of symmetric multiprocessing in which one or more processors are connected with a memory that stores an operating system in a machine executable form, the method comprising the steps of:

receiving an operating system call from a first thread, wherein the operating system call comprises a kernel call portion that requires access to a critical area of the operating system and an external call portion that requires access to a non-critical area of the operating system;

acquiring a global lock associated with the operating system for the first thread before accessing the critical area of the operating system for the kernel call portion of the operating system call; and

releasing the global lock upon completing the kernel call portion of the operating system call.

2. The method of claim 1, further comprising:

receiving an operating system call from a second thread that requires access to the non-critical area of the operating system; and

executing the first thread concurrently with the second thread.

3. The method of claim 2, wherein the step of executing comprises executing the first thread on a first processor of the one or more processors concurrently with execution of the second thread on a second processor of the one or more processors.

4. The method of claim 1, further comprising:

receiving an operating system call from a second thread that requires access to the critical area of the operating system; and

blocking the second thread from accessing the critical area of the operating system while the global lock is reserved for the first thread.

5. The method of claim 1, wherein the operating system call from the first thread is a first operating system call, the method further comprising:

receiving a second operating system call from a second thread, wherein the second operating system call comprises a kernel call portion that requires access to the critical area of the operating system and an external call portion that requires access to the non-critical area of the operating system; and

managing the global lock of the operating system to prevent overlapping execution of the kernel call portion of the first operating system call and the kernel call portion of the second operating system call.

6. The method of claim 5, further comprising allowing overlapping execution of the kernel call portion of the first operating system call and the external call portion of the second operating system call.

7. The method of claim 5, further comprising allowing overlapping execution of the external call portion of the first operating system call and the kernel call portion of the second operating system call.

8. A computer system comprising:

one or more processors;

a first memory storing an operating system in a machine executable form;

a second memory storing a lock manager in an machine executable form; and

a communication network interconnecting the one or more processors, the first memory, and the second memory;

wherein the lock manager is configured to;

receive an operating system call from a first thread, wherein the operating system call comprises a kernel call portion that requires access to a critical area of the operating system and an external call portion that requires access to a non-critical area of the operating system;

acquire a global lock associated with the operating system for the first thread to access the critical area of the operating system for the kernel call portion of the operating system call; and

release the global lock upon completing the kernel call portion of the operating system call.

9. The computer system of claim 8, wherein the lock manager is further configured to:

receive an operating system call from a second thread that requires access to the non-critical area of the operating system; and

allow the one or more processors to execute the first thread concurrently with the second thread.

10. The computer system of claim 9, wherein a first processor of the one or more processors is configured to execute the first thread concurrently with execution of the second thread on a second processor of the one or more processors.

11. The computer system of claim 8, wherein the lock manager is further configured to:

receive an operating system call from a second thread that requires access to the critical area of the operating system; and

block the second thread from accessing the critical area of the operating system while the global lock is reserved for the first thread.

12. The computer system of claim 8, wherein the operating system call from the first thread is a first operating system call, wherein the lock manager is further configured to:

receive a second operating system call from a second thread, wherein the second operating system call comprises a kernel call portion that requires access to the critical area of the operating system and an external call portion that requires access to the non-critical area of the operating system; and

manage the global lock of the operating system to prevent overlapping execution of the kernel call portion of the first operating system call and the kernel call portion of the second operating system call.

13. The computer system of claim 12, wherein the lock manager is further configured to allow overlapping execution of the kernel call portion of the first operating system call and the external call portion of the second operating system call.

14. The computer system of claim 12, wherein the lock manager is further configured to allow overlapping execution of the external call portion of the first operating system call and the kernel call portion of the second operating system call.

15. A non-transitory machine-readable medium with software stored thereon, wherein the software is executable by a processor to cause the processor to perform the steps of:

receiving an operating system call from a first thread, wherein the operating system call comprises a kernel call portion that requires access to a critical area of an operating system and an external call portion that requires access to a non-critical area of the operating system;

acquiring a global lock associated with the operating system for the first thread to access the critical area of the operating system for the kernel call portion of the operating system call; and

releasing the global lock upon completing the kernel call portion of the operating system call.

16. The non-transitory machine-readable medium of claim 15, wherein the software is executable by the processor to cause the processor to perform the steps of:

receiving an operating system call from a second thread that requires access to the non-critical area of the operating system; and

executing the first thread concurrently with the second thread.

17. The non-transitory machine-readable medium of claim 16, wherein the step of executing comprises executing the first thread on a first processor of the one or more processors concurrently with execution of the second thread on a second processor of the one or more processors.

18. The non-transitory machine-readable medium of claim 15, wherein the software is executable by the processor to cause the processor to perform the steps of:

receiving an operating system call from a second thread that requires access to the critical area of the operating system; and

blocking the second thread from accessing the critical area of the operating system while the global lock is reserved for the first thread.

19. The non-transitory machine-readable medium of claim 15, wherein the operating system call from the first thread is a first operating system call, wherein the software is executable by the processor to cause the processor to perform the steps of:

receiving a second operating system call from a second thread, wherein the second operating system call comprises a kernel call portion that requires access to the critical area of the operating system and an external call portion that requires access to the non-critical area of the operating system; and

managing the global lock of the operating system to prevent overlapping execution of the kernel call portion of the first operating system call and the kernel call portion of the second operating system call.

20. The non-transitory machine-readable medium of claim 19, wherein the software is executable by the processor to cause the processor to perform the step of allowing overlapping execution of the kernel call portion of the first operating system call and the external call portion of the second operating system call.

21. The non-transitory machine-readable medium of claim 19, wherein the software is executable by the processor to cause the processor to perform the step of allowing overlapping execution of the external call portion of the first operating system call and the kernel call portion of the second operating system call.

22. A method of symmetric multiprocessing in which one or more processors are connected with a first memory storing an operating system in a machine executable form, wherein the operating system comprises a critical area and a non-critical area, the method comprising the steps of:

responding to a first thread requiring an operating system call to the critical area of the operating system by requesting a global lock of the operating system for the first thread;

responding to the global lock being available by performing the steps of;

acquiring the global lock for the first thread to access the critical area of the operating system;

performing the operating system call to the critical area of the operating system, wherein the non-critical area of the operating system is available for access by a second thread while the global lock is applied to the critical area of the operating system for the first thread; and

releasing the global lock.

23. The method of claim 22, wherein the operating system call comprises a kernel call portion that requires access to the critical area of the operating system and an external call portion that requires access to the non-critical area of the operating system;

wherein the step of acquiring the global lock comprises the step of acquiring the global lock for the first thread to access the critical area of the operating system for the kernel call portion of the operating system call; and

wherein the step of releasing the global lock comprises the step of releasing the global lock upon completing the kernel call portion of the operating system call.