SYSTEM AND METHOD FOR HANDLING DATA ACCESS

• US 20090150401A1
• Filed: 12/10/2007
• Published: 06/11/2009
• Est. Priority Date: 12/10/2007
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Allen, James Johnson JR., Jenkins, Steven Kenneth, Trombley, Michael Raymond, Mossman, James A.
• Granted Patent: US 9,053,031 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0862 with prefetch

Abstract

A method for handling speculative access requests for a storage device in a computer system is provided. The method includes the steps of providing a speculative access threshold corresponding to a selected percentage of the total number of accesses to be speculatively issued, and intermixing demand accesses and speculative accesses in accordance with the speculative access threshold. In another embodiment, a method for reducing data access latency experienced by a user in a computer network is provided. The method includes the steps of providing a web page comprising a link to a data file stored on a database connected to the computer network, selecting a speculative access threshold corresponding to a selected percentage of data accesses which are to be speculatively provided to the user, and speculatively providing the data file in accordance with the speculative access threshold.

Claims

1. A method for handling speculative access requests for a storage device in a computer system comprising the steps of:

providing a speculative access threshold corresponding to a selected percentage of the total number of accesses to be speculatively issued; and

intermixing demand accesses and speculative accesses in accordance with the speculative access threshold.

2. The method of claim 1, further comprising the steps of:

dispatching an incoming access request speculatively if current storage device bandwidth being used for speculative accesses is less than the speculative access threshold; and

preventing the incoming access request from dispatching as a speculative access request if current storage device resources being used for speculative accesses is equal to or greater than the speculative access threshold.

3. The method of claim 2, further comprising the step of preventing the incoming access from dispatching as a speculative access if the storage device can not accept any more access requests.

4. The method of claim 3, further comprising the step of determining the speculative access threshold based on a system access request rate.

5. The method of claim 4, further comprising the step of determining the speculative access threshold based on a percentage of access requests that do not have valid cached data available and require data from the storage device.

6. A computer system comprising

a CPU;

a storage device;

circuitry for providing a speculative access threshold corresponding to a selected percentage of the total number of accesses to the storage device that can be speculatively issued; and

circuitry for intermixing demand accesses and speculative accesses in accordance with the speculative access threshold.

7. The computer system of claim 6, further comprising:

circuitry for dispatching an incoming access request speculatively if current storage device bandwidth being used for speculative accesses is less than the speculative access threshold; and

circuitry for preventing the incoming access request from dispatching as a speculative access request if current storage device resources being used for speculative accesses is equal to or greater than the speculative access threshold.

8. The computer system of claim 7, further comprising circuitry for preventing the incoming access from dispatching as a speculative access if the storage device can not accept any more access requests.

9. The computer system of claim 8, further comprising circuitry for determining the speculative access threshold based on a system access request rate.

10. The computer system of claim 9, further comprising circuitry for determining the speculative access threshold based on a percentage of access requests that do not have valid cached data available and require data from the storage device.

11. A computer program product embodied in a computer readable medium for handling speculative access requests for a storage device in a computer system comprising the programming steps of:

providing a speculative access threshold corresponding to a selected percentage of the total number of accesses to the storage device that can be speculatively issued; and

intermixing demand accesses and speculative accesses in accordance with the speculative access threshold.

12. The computer program product of claim 11, further comprising the programming steps of:

dispatching an incoming access request speculatively if current storage device bandwidth being used for speculative accesses is less than the speculative access threshold; and

preventing the incoming access request from issuing as a speculative access request if current storage device resources being used for speculative accesses is equal to or greater than the speculative access threshold.

13. The computer program product of claim 12, further comprising the programming step of preventing the incoming access request from issuing as a speculative access request if the storage device can not accept any more access requests.

14. The computer program product of claim 13, further comprising the programming step of determining the speculative access threshold based on a system access request rate.

15. The computer program product of claim 13, further comprising the programming step of determining the speculative access threshold based on a percentage of access requests that do not have valid cached data available and require data from the storage device.

16. A method for reducing data access latency experienced by a user in a computer network comprising the steps of:

providing a web page comprising a link to a data file stored on a database connected to the computer network;

selecting a speculative access threshold corresponding to a selected percentage of data accesses which are to be speculatively provided to the user; and

speculatively providing the data file in accordance with the speculative access threshold.

17. The method of claim 16, further comprising the steps of:

selecting the speculative access threshold based on a bandwidth limited resource of the computer network; and

monitoring the bandwidth limited resource.

18. The method of claim 17, wherein the bandwidth limited resource comprises available CPU resources.

19. The method of claim 17, wherein the bandwidth limited resource comprises available database bandwidth.

20. The method of claim 17, wherein the bandwidth limited resource comprises available network bandwidth.