Symmetric multi-processor system

• US 20070130567A1
• Filed: 09/05/2006
• Published: 06/07/2007
• Est. Priority Date: 08/25/1999
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: QNX Software Systems Limited (Canada) (Blackberry Limited)
• Inventors: Van Der Veen, Peter
• Granted Patent: US 7,996,843 B2
• Time in Patent Office: Days
• US Class Current: 718/102
• 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 medium 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, said method comprising the steps within said thread scheduler of:

responding to a thread requiring a call to said micro kernel operating system by requesting a global lock;

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

acquiring said global lock from said thread scheduler;

performing said call to said micro kernel operating system; 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 said step of executing said thread on said pre-emptable micro kernel operating system; and

reinstating said pre-empted threads following said step of executing said 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 thread;

locking said pre-emptable micro kernel operating system; and

exiting said pre-emptable micro kernel operating system.

4. A method of symmetric multiprocessing in which one or more processors, a first memory medium 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, said method comprising the steps within said thread scheduler of:

responding to a thread requiring a call to said micro kernel operating system by requesting a global lock;

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

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

acquiring said global lock from said thread scheduler;

entering said pre-emptable micro kernel operating system;

executing operating system functions as required by said thread;

locking said pre-emptable micro kernel operating system;

exiting said pre-emptable micro kernel operating system;

releasing said global lock; and

reinstating said pre-empted threads.

5. A computer system comprising:

one or more processors;

a first memory medium storing a pre-emptable operating system in a machine executable form;

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 being operable to;

responding to a thread requiring access to a critical area of said pre-emptable operating system by requesting a global lock;

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

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

executing said critical thread on said operating system; and

reinstating said pre-empted threads.