System and method for handling data access

• US 9,053,031 B2
• Filed: 12/10/2007
• Issued: 06/09/2015
• Est. Priority Date: 12/10/2007
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Allen, James Johnson Jr., Jenkins, Steven Kenneth, Mossman, James A., Trombley, Michael Raymond
• Primary Examiner(s): KROFCHECK, MICHAEL C
• Application Number:
  US11/953,201
• Publication Number:
  US 20090150401A1
• Time in Patent Office: 2,738 Days
• Field of Search: None
• 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 a total number of accesses to be speculatively issued, wherein said speculative access threshold is determined by an equation using one or more of the following;

a system access request rate and a percentage of access requests that do not have valid cached data available and require data from the storage device; 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, wherein the speculative access threshold is based on said system access request rate.

5. The method of claim 4, wherein the speculative access threshold is further based on said 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 a total number of accesses to the storage device that can be speculatively issued, wherein said speculative access threshold is determined by an equation using one or more of the following;

a system access request rate and a percentage of access requests that do not have valid cached data available and require data from the storage device; 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, wherein the speculative access threshold is based on said system access request rate.

10. The computer system of claim 9, wherein the speculative access threshold is further based on said 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 storage 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 a total number of accesses to the storage device that can be speculatively issued, wherein said speculative access threshold is determined by an equation using one or more of the following;

a system access request rate and a percentage of access requests that do not have valid cached data available and require data from the storage device; 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, wherein the speculative access threshold is based on said system access request rate.

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