System and method for increasing OS idle loop performance in a simulator

• US 7,343,590 B2
• Filed: 06/25/2002
• Issued: 03/11/2008
• Est. Priority Date: 06/25/2002
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Jacunski, Matt, Tormey, Daniel, Bolding, Joe
• Primary Examiner(s): Jones; Hugh
• Assistant Examiner(s): GEBRESILASSIE, KIBROM K
• Application Number:
  US10/178,992
• Publication Number:
  US 20030237075A1
• Time in Patent Office: 2,086 Days
• Field of Search: 703/21, 703/19, 703/22, 718/100, 718/107, 718/108, 717/131, 717/135, 719/328, 719/329
• US Class Current: 717/131
• CPC Class Codes: G06F 30/33 Design verification, e.g. functional simulation or model checking
• CPC Class Codes: G06F 9/455 Emulation; Interpretation; Software simulation, e.g. virtualisation or emulation of application or operating system execution engines
• CPC Class Codes: G06F 9/45533 Hypervisors; Virtual machine monitors
• CPC Class Codes: G06F 9/50 Allocation of resources, e.g. of the central processing unit [CPU]

Abstract

A system and method for increasing Operating System (OS) idle loop performance in a simulator environment. Upon encountering an OS idle loop condition on a processor, OS program flow is skipped ahead by an amount of time, thereby conserving the host machine'"'"'s resources that would otherwise have been spent in supporting the OS idle loop execution. If another processor initiates an inter-processor message directed to a processor whose OS program flow has been skipped forward, that processor is capable of skipping backward in time, if necessary, to service the inter-processor message.

Claims

1. A computer-implemented method of improving performance in a simulator environment operable to simulate a platform having a plurality of simulated processors, said platform running an Operating System (OS) program, the method comprising:

skipping ahead said OS program'"'"'s flow on a first simulated processor by an amount of time (T_Δ

) in response to said OS program entering an idle loop condition at time T₀ on said first simulated processor, thereby avoiding said idle loop condition by said OS program such that execution of instructions is inhibited on said first simulated processor; and

continuing to execute said OS program on said first simulated processor after skipping ahead by said amount of time T_Δ

, whereby system resources associated with a host system upon which said simulator environment is executed are conserved.

2. The computer-implemented method of improving performance in a simulator environment as set forth in claim 1, wherein said first simulated processor'"'"'s flow is skipped ahead from time T₀ by said amount of time T_Δ

, the method further comprising the step of continuing to execute said OS program on a second simulated processor during said time T_Δ

.

3. The computer-implemented method of improving performance in a simulator environment as set forth in claim 1, wherein said first simulated processor'"'"'s flow is skipped ahead to a time T_Δ

that is equal to T₀+T_Δ

, the method further comprising;

upon receiving an inter-processor message from a second simulated processor directed to said first simulated processor at time T₁, where T1 is between T₀ and T_A, skipping backward said OS program'"'"'s flow on said first simulated processor to time T₁, servicing said inter-processor message by said first simulated processor, and thereafter, skipping forward said OS program'"'"'s flow on said first simulated processor to time T_A.

4. The computer-implemented method of improving performance in a simulator environment as set forth in claim 1, wherein said amount of time T_Δ

is predetermined.

5. The computer-implemented method of improving performance in a simulator environment as set forth in claim 1, wherein said amount of time T_Δ

is determined based on an amount of time said OS program is to remain in said idle loop condition.

6. The computer-implemented method of improving performance in a simulator environment as set forth in claim 1, wherein said amount of time T_Δ

is determined based on when an external interrupt is to be serviced by said OS program.

7. The computer-implemented method of improving performance in a simulator environment as set forth in claim 1, wherein said amount of time T_Δ

is determined pursuant to a timer-based time duration.

8. The computer-implemented method of improving performance in a simulator environment as set forth in claim 1, wherein said amount of time T_Δ

is determined based on a minimum of a timer-based time duration and the time when an external interrupt is to be serviced by said OS program.

9. The computer-implemented method of improving performance in a simulator environment as set forth in claim 1, wherein said step of skipping ahead said OS program'"'"'s flow is effectuated by executing a simulator application program interface (API) routine operable to be executed on said platform.

10. A computer-implemented system for improving performance in a simulator environment operable to simulate a platform having a plurality of simulated processors, said platform running an Operating System (OS) program, the system comprising:

means for skipping ahead said OS program'"'"'s flow on a first simulated processor by a predetermined amount of time T_Δ

in response to said OS program entering an idle loop condition at time T₀ on said first simulated processor, thereby avoiding said idle loop condition by said OS program such that execution of instructions is inhibited on said first simulated processor; and

means for continuing to execute said OS program on said first simulated processor after skipping ahead by said amount of time T_Δ

, whereby system resources associated with a host system upon which said simulator environment is executed are conserved.

11. The computer-implemented system for improving performance in a simulator environment as set forth in claim 10, wherein said first simulated processor'"'"'s flow is skipped ahead from time T₀ by said amount of time T_Δ

, the system further comprising means for continuing to execute said OS program on a second simulated processor during said time T_Δ

.

12. The computer-implemented system for improving performance in a simulator environment as set forth in claim 10, wherein said first simulated processor'"'"'s flow is skipped ahead to a time T_A that is equal to T₀+T_Δ

, the system further comprising;

responsive to a second simulated processor initiating an inter-processor message directed to said first processor at time T₁ that is between T₀ and T_Δ

, means for skipping backward said OS program'"'"'s flow on said first processor to time T₁, means for servicing said inter-processor message by said first simulated processor, and means for skipping forward said OS program'"'"'s flow on said first simulated processor to time T_A after servicing said inter-processor message.

13. The computer-implemented system for improving performance in a simulator environment as set forth in claim 10, wherein said amount of time T_Δ

is predetermined.

14. The computer-implemented system for improving performance in a simulator environment as set forth in claim 10, wherein said amount of time T_Δ

is determined based on an amount of time said OS program is to remain in said idle loop condition.

15. The computer-implemented system for improving performance in a simulator environment as set forth in claim 10, wherein said amount of time T_Δ

is determined based on when an external interrupt is to be serviced by said OS program.

16. The computer-implemented system for improving performance in a simulator environment as set forth in claim 10, wherein said amount of time T_Δ

is determined pursuant to a timer-based time duration.

17. The computer-implemented system for improving performance in a simulator environment as set forth in claim 10, wherein said amount of time T_Δ

is determined based on a minimum of a timer-based time duration and the time when an external interrupt is to be serviced by said OS program.

18. The computer-implemented system for improving performance in a simulator environment as set forth in claim 10, wherein said means for skipping ahead said OS program'"'"'s flow comprises a simulator application program interface (API) routine operable to be executed on said platform.

19. A computer-implemented method of improving performance in a simulator environment operable to simulate a multiprocessor platform, said multiprocessor platform running an Operating System (OS) program, the method comprising:

upon encountering an OS idle loop condition at time T₀ on a first simulated processor, skipping ahead said OS program'"'"'s flow on said first simulated processor by an amount of time T_Δ

to time T_A, thereby avoiding said idle loop condition by said OS program such that execution of instructions is inhibited on said first simulated processor; and

responsive to a second simulated processor initiating an inter-processor message directed to said first processor at time T₁, where T₁ is between T₀ and T_A, skipping backward said OS program'"'"'s flow on said first simulated processor to time T₁, servicing said inter-processor message by said first simulated processor, and thereafter, skipping forward said OS program'"'"'s flow on said first simulated processor to time T_A, whereby system resources associated with a host system upon which said simulator environment is executed are conserved.

20. The computer-implemented method of improving performance in a simulator environment as set forth in claim 19, further comprising the step of continuing to execute said OS program on said first and second simulated processors when said second simulated processor reaches time T_A.

21. The computer-implemented method of improving performance in a simulator environment as set forth in claim 19, further comprising the step of providing a return message by said first simulated processor to said second simulated processor in response to said inter-processor message.

22. The computer-implemented method of improving performance in a simulator environment as set forth in claim 19, wherein said step of skipping ahead said OS program'"'"'s flow on said first simulated processor is effectuated by a simulator application program interface (API) routine operable to be executed on said first simulated processor.

23. The computer-implemented method of improving performance in a simulator environment as set forth in claim 19, wherein said step of skipping backward said OS program'"'"'s flow on said first simulated processor is effectuated by a simulator API routine operable to be executed on said first simulated processor.

24. The computer-implemented method of improving performance in a simulator environment as set forth in claim 19, wherein said inter-processor message comprises an interrupt.

25. The computer-implemented method of improving performance in a simulator environment as set forth in claim 19, wherein said amount of time T_Δ

is determined based on a minimum of a timer-based time duration associated with said first simulated processor and the time when an external interrupt is to be serviced by said first simulated processor.

26. A computer-implemented system for improving performance in a simulator environment operable to simulate a multiprocessor platform, said multiprocessor platform running an Operating System (OS) program, the system comprising:

means for skipping ahead said OS program'"'"'s flow on a first simulated processor by an amount of time T_Δ

to time T_A upon encountering an OS idle loop condition at time T₀ on said first simulated processor, thereby avoiding said idle loop condition by said OS program such that execution of instructions is inhibited on said first simulated processor;

means for skipping backward said OS program'"'"'s flow on said first simulated processor to time T₁, which is between T₀ and T_A, said means operating responsive to a second simulated processor initiating an inter-processor message directed to said first simulated processor at time T₁; and

means for skipping forward said OS program'"'"'s flow on said first simulated processor to time T_A upon servicing said inter-processor message by said first simulated processor, whereby system resources associated with a host system upon which said simulator environment is executed are conserved.

27. The computer-implemented system for improving performance in a simulator environment as set forth in claim 26, wherein said means for skipping ahead said OS program'"'"'s flow on said first simulated processor by said amount of time T_Δ

to time T_A comprises a simulator application program interface (API) routine operable to be executed on said first simulated processor.

28. The computer-implemented system for improving performance in a simulator environment as set forth in claim 26, wherein said means for skipping backward said OS program'"'"'s flow on said first simulated processor to time T₁ comprises a simulator API routine operable to be executed on said first simulated processor.

29. The computer-implemented system for improving performance in a simulator environment as set forth in claim 26, wherein said amount of time T_Δ

is determined based on a minimum of a timer-based time duration associated with said first simulated processor and the time when an external interrupt is to be serviced by said first simulated processor.