Motivating lazy RCU callbacks under out-of-memory conditions

• US 8,972,801 B2
• Filed: 02/04/2013
• Issued: 03/03/2015
• Est. Priority Date: 02/04/2013
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: McKenney, Paul E.
• Primary Examiner(s): Baderman, Scott
• Assistant Examiner(s): KUDIRKA, JOSEPH R
• Application Number:
  US13/758,778
• Publication Number:
  US 20140223242A1
• Time in Patent Office: 757 Days
• Field of Search: 714/54
• US Class Current: 714/54
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

A technique for motivating lazy RCU callbacks under out-of-memory conditions. In response to detecting an actual or potential OOM condition, non-lazy callback processing is performed for all processors whose RCU callback lists are non-empty due to at least one callback permitting lazy callback processing being present.

Claims

1. In a computing system having one or more processors operatively coupled to one or more memory devices, a method for motivating lazy read-copy update (RCU) callbacks under out-of-memory (OOM) conditions, the method comprising:

detecting an actual or potential OOM condition; and

performing non-lazy callback processing for all processors whose RCU callback lists are non-empty due to at least one callback permitting lazy callback processing being present.

2. A method in accordance with claim 1, wherein said detecting comprises detecting an actual OOM condition based on an operating system notification.

3. A method in accordance with claim 1, wherein said detecting comprises detecting a potential OOM condition based on a backlog of pending callbacks.

4. A method in accordance with claim 1, wherein said at least one callback permitting lazy callback processing comprises either any callback or any lazy callback.

5. A method in accordance with claim 1, wherein said performing comprises enqueuing a non-lazy callback on each RCU callback list having said at least one callback permitting lazy callback processing.

6. A method in accordance with claim 1, wherein said performing comprises setting a non-lazy mode wherein all pending callbacks are treated as non-lazy.

7. A method in accordance with claim 6, wherein said performing comprises processing said RCU callback lists until either each affected callback list is emptied or is reduced to a predetermined size.

8. A system, comprising:

one or more processors; and

a memory coupled to said one or more processors, said memory including a computer useable medium tangibly embodying at least one program of instructions executable by said processor to perform operations for motivating lazy read-copy update (RCU) callbacks under out-of-memory (OOM) conditions, said operations comprising;

detecting an actual or potential OOM condition; and

performing non-lazy callback processing for all processors whose RCU callback lists are non-empty due to at least one callback permitting lazy callback processing being present.

9. A system in accordance with claim 8, wherein said detecting comprises detecting an actual OOM condition based on an operating system notification.

10. A system in accordance with claim 8, wherein said detecting comprises detecting a potential OOM condition based on a backlog of pending callbacks.

11. A system in accordance with claim 8, wherein said at least one callback permitting lazy callback processing comprises either any callback or any lazy callback.

12. A system in accordance with claim 8, wherein said performing comprises enqueuing a non-lazy callback on each RCU callback list having said at least one callback permitting lazy callback processing.

13. A system in accordance with claim 8, wherein said performing comprises setting a non-lazy mode wherein all pending callbacks are treated as non-lazy.

14. A system in accordance with claim 13, wherein said performing comprises processing said RCU callback lists until either each affected callback list is emptied or is reduced to a predetermined size.

15. A computer program product, comprising:

one or more non-transitory machine-useable storage media; and

program instructions provided by said one or more media for programming a data processing platform to perform operations for motivating lazy read-copy update (RCU) callbacks under out-of-memory (OOM) conditions, said operations comprising;

detecting an actual or potential OOM condition; and

performing non-lazy callback processing for all processors whose RCU callback lists are non-empty due to at least one callback permitting lazy callback processing being present.

16. A computer program product in accordance with claim 15, wherein said detecting comprises detecting an actual OOM condition based on an operating system notification.

17. A computer program product in accordance with claim 16, wherein said detecting comprises detecting a potential OOM condition based on a backlog of pending callbacks.

18. A computer program product in accordance with claim 16, wherein said at least one callback permitting lazy callback processing comprises either any callback or any lazy callback.

19. A computer program product in accordance with claim 16, wherein said performing comprises enqueuing a non-lazy callback on each RCU callback list having said at least one callback permitting lazy callback processing.

20. A computer program product in accordance with claim 16, wherein said performing comprises setting a non-lazy mode wherein all pending callbacks are treated as non-lazy.

21. A computer program product in accordance with claim 20, wherein said performing comprises processing said RCU callback lists until either each affected callback list is emptied or is reduced to a predetermined size.