System and method for application influence of I/O service order post I/O request

• US 6,292,856 B1
• Filed: 01/29/1999
• Issued: 09/18/2001
• Est. Priority Date: 01/29/1999
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Marcotte, Scott Thomas
• Primary Examiner(s): Shin, Christopher B.
• Application Number:
  US09/240,719
• Time in Patent Office: 963 Days
• Field of Search: 709/100-107, 710/5-7, 710/22-30, 710/36-45, 710/52-57, 710/260-263, 711/3, 711/117
• US Class Current: 710/39
• CPC Class Codes: G06F 13/102 where the programme performs an interfacing function, e.g. device driver G06F13/105 takes precedence; scheduling within device drivers G06F9/52; contention policies within device drivers G06F9/4881
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0671 In-line storage system

Abstract

System and method for scheduling I/O requests in a multi-tasking data processing environment. An I/O request issued by an application is placed in an I/O request holding queue. Under control of the requesting application (or, alternatively, the operating system), the I/O request is selectively canceled or moved to a service pending queue for execution. Requests can be moved either by the application or by the Operating system when an I/O completes (and hence the service pending queue has room for another IO).

Claims

1. A method for scheduling at least one I/O request, comprising the steps of:

issuing said I/O request to a device driver;

placing said I/O request in an I/O request holding queue; and

under control of the entity issuing said I/O request to said device driver, selectively canceling or moving said I/O request to a service pending queue for execution.

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

serving to said entity information regarding contents of said request holding queue and selectively of said service pending queue; and

operating said entity responsive to said information to influence the order of execution of I/O requests in said holding queue.

3. The method of claim 2, said entity residing at the application level of a data processing system.

4. The method of claim 2, said entity residing at the operating system level of a data processing system.

5. A method for operating a device driver for scheduling input/output requests, comprising the steps of:

receiving a plurality of I/O requests into a holding queue;

responsive to user request, selectively either canceling or moving specific I/O request from said holding queue to a service queue; and

executing I/O requests in said service queue.

6. A method for scheduling input/output requests, comprising the steps of:

queuing scheduled requests; and

responsive to events subsequent to said queuing step,

selectively either canceling or moving a queued to a service queue for execution.

7. The method of claim 6, further comprising the step of:

operating a user application to monitor said events and to initiate said either canceling or moving step.

8. The method of claim 7, further comprising the steps of:

queuing newly scheduled requests in a holding queue;

upon said user application initiating said either canceling or moving step for a selected request, moving said selected request from said holding queue to a service queue.

9. The method of claim 6, further comprising the step of:

further responsive to events subsequent to said queuing step, selectively canceling a queued request.

10. The method of claim 8, further comprising the step of:

removing I/O requests from said holding queue and scheduling them to said service queue when the count of outstanding I/O requests falls below a specified threshold.

11. A system for scheduling an I/O request, comprising:

a device driver;

an input/output interface for issuing said I/O request to said device driver;

an I/O request holding queue for holding said I/O request upon being issued to said device driver;

until selectively either canceled or moved to a service pending queue;

said service pending queue, responsive to a command from an entity issuing said I/O request to said device driver, for selectively canceling or receiving said I/O request from said holding queue for execution.

12. A system for scheduling input/output requests for a user application, comprising:

a holding queue for receiving a plurality of scheduled I/O requests;

said application selectively either canceling or moving said I/O requests from said holding queue to a service queue;

said service queue for executing I/O requests moved from said holding queue responsive to a command from said user application.

13. A system for scheduling input/output requests, comprising:

means for queuing scheduled requests; and

means responsive to events subsequent to said queuing step for selectively either canceling or moving said requests from said queuing means to a service queue for executing queued requests.

14. A program storage device readable by a machine, tangibly embodying a program of instructions executable by a machine to perform method steps for scheduling at least one I/O request, said method steps comprising:

issuing said I/O request to a device driver;

placing said I/O request in an I/O request holding queue; and

under control of the entity issuing said I/O request to said device driver, selectively either canceling or moving said I/O request to a service pending queue for execution.

15. An article of manufacture comprising:

a computer useable medium having computer readable program code means embodied therein for scheduling I/O requests, the computer readable program means in said article of manufacture comprising;

computer readable program code means for causing a computer to effect issuing said I/O request to a device driver;

computer readable program code means for causing a computer to effect placing said I/O request in an I/O request holding queue; and

computer readable program code means for causing a computer to effect under control of the entity issuing said I/O request to said device driver, selectively either canceling or moving said I/O request to a service pending queue for execution.