Dual Mode Operating System For A Computing Device

• US 20090100429A1
• Filed: 03/01/2006
• Published: 04/16/2009
• Est. Priority Date: 03/02/2005
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Symbian Software Limited (Accenture PLC)
• Inventors: May, Dennis, Thoelke, Andrew
• Granted Patent: US 8,332,856 B2
• Time in Patent Office: Days
• US Class Current: 718/102
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 12/1027 using associative or pseudo-associative address translation means, e.g. translation look-aside buffer [TLB]
• CPC Class Codes: G06F 12/126 with special data handling, e.g. priority of data or instructions, handling errors or pinning

Abstract

A computing device which runs non-pageable real time and pageable non-real time processes is provided with non-pageable real time and pageable non-real time versions of operating system services where the necessity to page in memory would block a real-time thread of execution. In one embodiment, a real time operating system service has all its code and data locked, and only supports clients that similarly have their code and data locked. This ensures that such a service will not block due to a page fault caused by client memory being unavailable. A non-real time operating system service does not have its data locked and supports clients whose memory can be paged out. In a preferred embodiment servers which are required to provide real time behaviour are multithreaded and arrange for requests from real time and non-real time clients to be serviced in different threads.

Claims

1. A method of providing real time performance with memory paging in a computing device, the method comprising

a. providing real time and non-real time versions of operating system services;

b. locking memory pages used for code and memory referenced by the real time versions of the said operating system services for preventing the said memory pages being paged out; and

c. causing real time applications, processes and threads to make use of the real time versions of the said operating system services.

2. A method according to claim 1 in which applications, processes and threads which do not have real-time priority are not permitted access to the real time versions of the operating system services.

3. A method according to claim 1 in which an application, process or thread is not permitted to access a real time version of an operating system service if it does not have a real-time capability or equivalent run-time permission.

4. A method according to claim 3 in which access to an operating system service by an application, process or thread is routed to either the real-time or non-real time version of that service depending on the capability or equivalent run-time permission of the application, process or thread.

5. A method according to claim 1 in which access to an operating system service by an application, process or thread is routed to either the real-time or non-real time version of the service depending on the priority of the application, process or thread.

6. A method according to claim 1 in which the real time and non-real time versions of at least one of the said operating system services are provided as separate threads of execution in a single multithreaded process.

7. A method according to claim 1 in which at least one of the operating system services is implemented as a server.

15. An operating system for causing a computing device according to claim 8 to operate in accordance with a method as claimed in claim 1.

8. A computing device arranged to provide real time performance with memory paging and comprising

a. real time and non-real time versions of operating system services;

b. means for locking memory pages used for code and memory referenced by the real time versions of the said operating system services for preventing the said memory pages being paged out; and

c. means for causing real time applications, processes and threads to make use of the real time versions of the said operating system services.

9. A device according to claim 8 wherein applications, processes and threads which do not have real-time priority are not permitted access to the real time versions of the operating system services.

10. A device according to claim 8 wherein an application, process or thread is not permitted to access a real time versions of an operating system service if it does not have a real-time capability or equivalent run-time permission.

11. A device according to claim 10 wherein access to an operating system service by an application, process or thread is routed to either the real-time or non-real time version of that service depending on the capability or equivalent run-time permission of the application, process or thread.

12. A device according to claim 8 wherein access to an operating system service by an application, process or thread is routed to either the real-time or non-real time version of the service depending on the priority of the application, process or thread.

13. A device according to claim 8 wherein the real time and non-real time versions of at least one of the said operating system services are provided as separate threads of execution in a single multithreaded process.

14. A device according to claim 8 wherein at least one of the operating system services is implemented as a server.