Operating system aware hardware mutex

• US 8,996,152 B2
• Filed: 06/28/2006
• Issued: 03/31/2015
• Est. Priority Date: 06/28/2006
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Terrell, James R.
• Primary Examiner(s): ZHE, MENG YAO
• Application Number:
  US11/427,015
• Publication Number:
  US 20080005740A1
• Time in Patent Office: 3,198 Days
• Field of Search: None
• US Class Current: 700/100
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

Hardware resource sharing for a computerized system running software tasks. A mutex controller is associated with the hardware resource. Lock and unlock indicators are settable by a software task and readable by the controller, and locked and waiters flags are settable and readable by the controller. The controller monitors whether the lock indicator has been set and determines whether the locked flag is set. If not, it sets the locked flag and, if so, it sets the waiters flag and asserts a mutex interrupt signaling the computer system to divert the software task to run a lock request routine. The controller also monitors whether the unlock indicator has been set and then determines whether the waiters flag is set. If not, it clears the locked flag and, if so, it asserts a mutex interrupt signaling the computer system to divert the software task to run an unlock request routine.

Claims

1. A method comprising:

setting a bit in a register via a software task, said setting indicates a request to lock a hardware mutex, said hardware mutex comprises said register;

after said setting, determining via a controller if said hardware mutex is locked, said hardware mutex comprises said controller;

if it is determined said hardware mutex is not locked, setting a first flag using said controller to lock said hardware mutex without interrupting a kernel of an operating system, wherein said controller is implemented using hardware; and

if it is determined said hardware mutex is locked, asserting via said controller an interrupt operable to interrupt said software task and enabling said kernel of said operating system to handle said request to lock said hardware mutex.

2. The method of claim 1, wherein said setting said first flag is performed transparently to said software task.

3. The method of claim 1 further comprising:

if it is determined said hardware mutex is locked, setting via said controller a second flag to indicate that said software task is waiting for said hardware mutex to unlock.

4. The method of claim 1 further comprising:

after said interrupt, saving a state of a processor executing said software task.

5. The method of claim 4, wherein said saving said state is performed by an interrupt exception handler of said processor.

6. The method of claim 4, wherein said saving said state further comprises saving data in at least one register of said processor, wherein said data comprises a parameter set by said software task, and wherein said parameter is selected from a group consisting of a wait timeout value, a block flag, and a non-blocking flag.

7. The method of claim 1 further comprising:

after said interrupt, identifying another software task operable to run and executing said another software task.

8. The method of claim 1

wherein said enabling is performed by an interrupt service routine of said controller.

9. The method of claim 1 wherein said determining if said hardware mutex is locked by determining if said first flag is set.

33. The method of claim 1, wherein said enabling is performed by said controller.

10. A system comprising:

a software task operable to set a bit in a register;

a hardware mutex comprising said register and a controller; and

said controller implemented using hardware, said controller operable to;

determine whether said software task has requested to lock said hardware mutex by monitoring if said bit is set in said register, said hardware mutex comprises said controller;

if said bit is set, determine if said hardware mutex is locked;

if it is determined said hardware mutex is not locked, set a first flag to lock said hardware mutex without interrupting a kernel of an operating system; and

if it is determined said hardware mutex is locked, assert an interrupt operable to interrupt said software task and enable said kernel of said operating system to handle said request to lock said hardware mutex.

11. The system of claim 10, wherein said controller is further operable to set said first flag in a manner that is transparent to said software task.

12. The system of claim 10, wherein said controller is further operable to set a second flag to indicate that said software task is waiting for said hardware mutex to unlock if said hardware mutex is locked.

13. The system of claim 10, wherein said asserting of said interrupt is operable to cause a saving of a state of a processor executing said software task.

14. The system of claim 13, wherein said saving said state is performed by an interrupt exception handler of said processor.

15. The system of claim 13, wherein said saving said state further comprises saving data in at least one register of said processor, wherein said data comprises a parameter set by said software task, and wherein said parameter is selected from a group consisting of a wait timeout value, a block flag, and a non-blocking flag.

16. The system of claim 10, wherein said controller is further operable to determine if said hardware mutex is locked by determining if said first flag is set.

17. A method comprising:

setting a bit in a register via a software task, said setting indicates a request to unlock a hardware mutex, said hardware mutex comprises said register;

after said setting, determining via a controller if another software task is waiting to lock said hardware mutex, said hardware mutex comprises said controller;

if it is determined no other software task is waiting to lock said hardware mutex, clearing a first flag using said controller to unlock said hardware mutex without interrupting a kernel of an operating system, wherein said controller is implemented using hardware; and

if it is determined another software task is waiting to lock said hardware mutex, asserting via said controller an interrupt operable to interrupt said software task and enabling said kernel of said operating system to handle said request to unlock said hardware mutex.

18. The method of claim 17, wherein said clearing is performed transparently to said software task.

19. The method of claim 17 further comprising:

after said interrupt, saving a state of a processor executing said software task.

20. The method of claim 19, wherein said saving said state is performed by an interrupt exception handler of said processor.

21. The method of claim 19, wherein said saving said state further comprises saving data in at least one register of said processor, wherein said data comprises a parameter set by said software task, and wherein said parameter is selected from a group consisting of a wait timeout value, a block flag, and a non-blocking flag.

22. The method of claim 17 further comprising:

after said interrupt, saving a state of a processor executing said software task and clearing a second flag, wherein said second flag indicates whether another software task is waiting to lock said hardware mutex.

23. The method of claim 17 further comprising:

after said interrupt, identifying another software task operable to run and executing said another software task.

24. The method of claim 17 further comprising:

wherein said enabling is performed by an interrupt service routine of said controller.

25. The method of claim 17 wherein said determining if another software task is waiting to lock said hardware mutex by determining if a second flag is set.

26. A system comprising:

a software task operable to set a bit in a register;

a hardware mutex comprising said register and a controller; and

said controller implemented using hardware, said controller operable to;

determine whether said software task has requested to unlock of said hardware mutex by monitoring if said bit is set in said register;

if said bit is set, determine if another software task is waiting to lock said hardware mutex;

if it is determined no other software task is waiting to lock said hardware mutex, clear a first flag to unlock said hardware mutex without interrupting a kernel of an operating system; and

if it is determined another software task is waiting to lock said hardware mutex, assert an interrupt operable to interrupt said software task and enable said kernel of said operating system to handle said request to unlock said hardware mutex.

27. The system of claim 26, wherein said controller is further operable to clear said first flag in a manner that is transparent to said software task.

28. The system of claim 26, wherein said asserting of said interrupt is operable to cause a saving of a state of a processor executing said software task.

29. The system of claim 28, wherein said saving said state is performed by an interrupt exception handler of said processor.

30. The system of claim 28, wherein said saving said state further comprises saving data in at least one register of said processor, wherein said data comprises a parameter set by said software task, and wherein said parameter is selected from a group consisting of a wait timeout value, a block flag, and a non-blocking flag.

31. The system of claim 26, wherein said asserting of said interrupt is operable to cause a saving of a state of a processor executing said software task and clearing a second flag, wherein said second flag indicates whether another software task is waiting to lock said hardware mutex.

32. The system of claim 26, wherein said controller is further operable to determine if another software task is waiting to lock said hardware mutex by determining if a second flag is set.