Symmetric multi-processor system

• US 7,996,843 B2
• Filed: 09/05/2006
• Issued: 08/09/2011
• Est. Priority Date: 08/25/1999
• Status: Expired due to Term

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: QNX Software Systems Company (Blackberry Limited)
• Inventors: Van Der Veen, Peter
• Primary Examiner(s): An, Meng A
• Assistant Examiner(s): Kawsar, Abdullah Al
• Application Number:
  US11/515,675
• Publication Number:
  US 20070130567A1
• Time in Patent Office: 1,799 Days
• Field of Search: None
• US Class Current: 718/104
• 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, a first memory storing a micro kernel operating system in a machine executable form and a second memory storing a thread scheduler in a machine executable form are interconnected via a communication network, wherein the micro kernel operating system comprises a critical area and a non-critical area, said method comprising the steps of:

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

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

acquiring said global lock from said thread scheduler for the first thread to access the critical area of the micro kernel operating system;

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

releasing said global lock.

2. A method of symmetric multiprocessing as claimed in claim 1, wherein said micro kernel operating system comprises a pre-emptable micro kernel operating system, said method further comprising the steps with said thread scheduler of:

pre-empting any non-critical threads currently executing on said pre-emptable micro kernel operating system prior to executing said first thread on said pre-emptable micro kernel operating system; and

reinstating said pre-empted threads following said step of executing said first thread on said pre-emptable micro kernel operating system.

3. A method of symmetric multiprocessing as claimed in claim 2 wherein said step of performing said call to said micro kernel operating system comprises the steps of:

entering said pre-emptable micro kernel operating system;

executing operating system functions as required by said first thread; and

exiting said pre-emptable micro kernel operating system.

4. The method of claim 1, where the act of releasing said global lock comprises releasing the global lock of the critical area before completing an operating system call of the non-critical area for the first thread.

5. The method of claim 1, where the critical area is limited to operating system message-passing capabilities and the non-critical area comprises operating system functionality delegated to external processes.

6. The method of claim 5, where the message-passing capabilities comprise inter-process control (IPC) message-passing services.

7. The method of claim 1, where the global lock comprises an only lock used by the micro kernel operating system to manage threads.

8. The method of claim 1, further comprising:

executing the first thread on a first processor of the one or more processors; and

executing the second thread on a second processor of the one or more processors.

9. A method of symmetric multiprocessing in which one or more processors, a first memory storing a pre-emptable micro kernel operating system in a machine executable form and a second memory storing a thread scheduler in a machine executable form are interconnected via a communication network, wherein the micro kernel operating system comprises a critical area and a non-critical area, said method comprising the steps of:

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

pre-empting any non-critical threads currently executing on said pre-emptable micro kernel operating system;

acquiring said global lock from said thread scheduler for the first thread to access the critical area of the micro kernel operating system;

entering said pre-emptable micro kernel operating system;

executing operating system functions of the critical area as required by said first thread, wherein the non-critical area of the micro kernel operating system is available for access by a second thread while the global lock is applied to the critical area of the micro kernel operating system for the first thread;

exiting the critical area of said pre-emptable micro kernel operating system;

releasing said global lock; and

reinstating said pre-empted threads.

10. A computer system comprising:

one or more processors;

a first memory storing a pre-emptable operating system in a machine executable form, wherein the operating system comprises a critical area and a non-critical area;

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

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

said lock manager configured to;

respond to a first thread requiring access to the critical area of said pre-emptable operating system by requesting a global lock of the critical area of the operating system for the first thread;

pre-empt any non-critical threads currently executing on said operating system;

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

execute the first thread on said 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

reinstate said pre-empted threads.

11. The computer system of claim 10, where the lock manager is further configured to release the global lock of the critical area before completing an operating system call of the non-critical area for the first thread.

12. The computer system of claim 10, where the critical area is limited to operating system message-passing capabilities and the non-critical area comprises operating system functionality delegated to external processes.

13. The computer system of claim 12, where the message-passing capabilities comprise inter-process control (IPC) message-passing services.

14. The computer system of claim 10, where the global lock comprises an only lock used by the operating system to manage threads.

15. The computer system of claim 10, where the one or more processors comprise a first processor to execute the first thread, and where the one or more processors comprise a second processor to execute the second thread.