Method and System for Scheduling User-Level I/O Threads

• US 20080263554A1
• Filed: 07/02/2008
• Published: 10/23/2008
• Est. Priority Date: 10/06/2004
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Rosu, Daniela, Rosu, Marcel Catalin
• Application Number:
  US12/166,450
• Publication Number:
  US 20080263554A1
• Time in Patent Office: Days
• US Class Current: 718/102
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues

Abstract

The present invention is directed to a user-level thread scheduler that employs a service that propagates at the user level, continuously as it gets updated in the kernel, the kernel-level state necessary to determine if an I/O operation would block or not. In addition, the user-level thread schedulers used systems that propagate at the user level other types of information related to the state and content of active file descriptors. Using this information, the user-level thread package determines when I/O requests can be satisfied without blocking and implements pre-defined scheduling policies.

Claims

1. A method for scheduling threads using a user-level thread scheduler, the method comprising:

using global state information published at a user level by a kernel module to determine a sequence for executing the threads;

wherein the published global state information comprises a sufficient amount of kernel-level information to permit the user-level thread scheduler to determine the sequence of executing the threads.

2. The method of claim 1, wherein the global state information comprises file descriptor information for active files.

3. The method of claim 1, wherein the step of using the global state information comprises determining if each thread can be executed without blocking.

4. The method of claim 1, wherein the step of using the global state information comprises:

assigning a value with each thread; and

determining the sequence of execution based upon the assigned thread values.

5. The method of claim 4, wherein the step of assigning a value comprises using one or more policies to determine the assigned value for each thread.

6. The method of claim 5, wherein the policies comprise available payload based policies, message-driven policies, application-specific policies or combinations thereof.

7. The method of claim 1, further comprising continuously publishing updated global state information at the user-level.

8. The method of claim 1, further comprising accessing the published global state information using conventional memory reads and writes, user-level library calls or combinations thereof.

9. A computer readable medium containing a computer executable code that when read by a computer causes the computer to perform a method for scheduling threads using a user-level thread scheduler, the method comprising:

using global state information published at a user level by a kernel module to determine a sequence for executing the threads;

wherein the published global state information comprises a sufficient amount of kernel-level information to permit the user-level thread scheduler to determine the sequence of executing the threads.

10. The computer readable medium of claim 9, wherein the global state information comprises file descriptor information for active files.

11. The computer readable medium of claim 9, wherein the step of using the global state information comprises determining if each thread can be executed without blocking.

12. The computer readable medium of claim 9, wherein the step of using the global state information comprises:

assigning a value with each thread; and

determining the sequence of execution based upon the assigned thread values.

13. The computer readable medium of claim 12, wherein the step of assigning a value comprises using one or more policies to determine the assigned value for each thread.

14. The computer readable medium of claim 13, wherein the policies comprise available payload based policies, message-driven policies, application-specific policies or combinations thereof.

15. The computer readable medium of claim 9, further comprising continuously publishing updated global state information at the user-level.

16. The computer readable medium of claim 9, further comprising accessing the published global state information using conventional memory reads and writes, user-level library calls or combinations thereof.

17. A user-level thread package comprising:

a user-level thread scheduler capable of scheduling execution of a plurality of threads based upon kernel-level state information published at the user-level;

wherein the user-level thread package utilizes a kernel-level state information propagation system to publish the kernel-level state information at the user-level.

18. The user-level thread package of claim 17, wherein the kernel-level state information propagation system comprises a file descriptor propagation system to publish file descriptor information for active files at the user level.