CANCEL INSTRUCTION AND COMMAND FOR DETERMINING THE STATE OF AN I/O OPERATION

• US 20090210560A1
• Filed: 02/14/2008
• Published: 08/20/2009
• Est. Priority Date: 02/14/2008
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kalos, Matthew J., Yudenfriend, Harry M., Huang, Catherine C., Flanagan, John R., Ricci, Louis W., Carlson, Scott M., Hathorn, Roger G., Sittmann, Gustav E., Njoku, Ugochukwu C., Casper, Daniel F., Riedy, Dale F.
• Granted Patent: US 8,166,206 B2
• Time in Patent Office: Days
• US Class Current: 710/5
• CPC Class Codes: G06F 13/122 where hardware performs an I/O function other than control of data transfer

Abstract

The state of an input/output (I/O) operation is determined in an I/O processing system. A command is received from an I/O operating system at a channel subsystem for initiating the I/O operation, a time period is for completion of the I/O operation, and the command for initiating the I/O operation is sent from the channel subsystem to the control unit. Responsive to the time period nearing elapsing without the I/O operation completing, a cancel instruction is received from the I/O operating system at the channel subsystem. Responsive to a determination by the I/O operating system to interrogate the control unit, an instruction to interrogate the control unit is received with the cancel instruction from the I/O operating system.

Claims

1. A computer program product for determining a state of an input/output (I/O) operation in an I/O processing system, comprising:

a tangible storage medium readable by a processing circuit and storing instructions for executing by the processing circuit for performing a method comprising;

receiving a command from an I/O operating system at a channel subsystem for initiating the I/O operation;

setting a time period for completion of the I/O operation;

sending the command for initiating the I/O operation from the channel subsystem to the control unit;

responsive to the time period nearing elapsing without the I/O operation completing, receiving a cancel instruction from the I/O operating system at the channel subsystem, wherein responsive to a determination by the I/O operating system to interrogate the control unit, an instruction to interrogate the control unit is received with the cancel instruction from the I/O operating system.

2. The computer program product of claim 1, wherein the further comprises, responsive to receipt of the instruction to interrogate the control unit from the I/O operating system, determining whether to send an interrogate command to the control unit to determine the state of the I/O operation being executed by an I/O device controlled by the control unit.

3. The computer program product of claim 2, wherein determining whether to send the interrogate command to the control unit for determining the state of the I/O operation includes determining whether the I/O operation has started.

4. The computer program product of claim 3, wherein the method further comprises discarding the instruction to interrogate the control unit responsive to a determination that the I/O operation has not started.

5. The computer program product of claim 2, wherein determining whether to send an interrogate command to the control unit for determining the state of the I/O operation includes determining whether an interrogation operation is already in progress.

6. The computer program product of claim 5, wherein the method further comprises discarding the instruction to interrogate the control unit responsive to a determination that an interrogation operation is already in progress.

7. The computer program product of claim 2, wherein the method further comprises, responsive to a determination to send an interrogation command to the control unit, sending the interrogation command to the control unit and receiving a response from the control unit indicating a state of the I/O device in response to receipt of the interrogation command by the control unit, wherein the response from the control unit indicates whether the I/O device is reserved by another I/O processing system.

8. An apparatus adapted for communicating with a control unit controlling an input/output (I/O) device for executing an I/O operation in an I/O processing system, the apparatus comprising:

a channel subsystem for communication with an I/O operating system and the control unit, the channel subsystem performing a method comprising;

receiving a command from the I/O operating system for initiating the I/O operation;

setting a time period for completion of the I/O operation;

sending the command for initiating the I/O operation to the control unit;

responsive to the time period nearing elapsing without the I/O operation completing, receiving a cancel instruction from the I/O operating system at the channel subsystem, wherein responsive to a determination by the I/O operating system to interrogate the control unit to determine a state of the I/O operation, an instruction to interrogate the control unit is received with the cancel instruction from the I/O operating system.

9. The apparatus of claim 8, wherein the method performed by the channel subsystem further comprises, responsive to receipt of the instruction to interrogate the control unit from the I/O operating system, determining whether to send an interrogate command to the control unit to determine the state of the I/O operation being executed by an I/O device controlled by the control unit.

10. The apparatus of claim 9, wherein as part of determining whether to send the interrogate command to the control unit for determining the state of the I/O operation, the channel subsystem determines whether the I/O operation has started.

11. The apparatus of claim 10, wherein the channel subsystem discards the instruction to interrogate the control unit responsive to a determination that the I/O operation has not started.

12. The apparatus of claim 9, wherein as part of determining whether to send an interrogate command to the control unit for determining the state of the I/O operation, the channel subsystem determines whether an interrogation operation is already in progress.

13. The apparatus of claim 12, wherein the channel subsystem discards the instruction to interrogate the control unit responsive to a determination that an interrogation operation is already in progress.

14. The apparatus of claim 9, wherein the method performed by the apparatus further comprises, responsive to a determination to send an interrogation command to the control unit, sending the interrogation command to the control unit and receiving a response from the control unit indicating a state of the I/O device in response to receipt of the interrogation command by the control unit, wherein the response from the control unit indicates whether the I/O device is reserved by another I/O processing system.

15. A method for determining a state of an input/output (I/O) operation in an I/O processing system, comprising:

receiving a command from an I/O operating system at a channel subsystem for initiating the I/O operation;

setting a time period for completion of the I/O operation;

sending the command for initiating the I/O operation from the channel subsystem to the control unit;

responsive to the time period nearing elapsing without the I/O operation completing, receiving a cancel instruction from the I/O operating system at the channel subsystem, wherein responsive to a determination by the I/O operating system to interrogate the control unit, an instruction to interrogate the control unit is received with the cancel instruction from the I/O operating system.

16. The method of claim 15, further comprising, responsive to receipt of the instruction to interrogate the control unit from the I/O operating system, determining whether to send an interrogate command to the control unit to determine the state of the I/O operation being executed by an I/O device controlled by the control unit.

17. The method of claim 16, wherein determining whether to send the interrogate command to the control unit for determining the state of the I/O operation includes determining whether the I/O operation has started.

18. The method of claim 17, further comprising discarding the instruction to interrogate the control unit responsive to a determination that the I/O operation has not started.

19. The method of claim 16, wherein determining whether to send an interrogate command to the control unit for determining the state of the I/O operation includes determining whether an interrogation operation is already in progress.

20. The method of claim 19, further comprising discarding the instruction to interrogate the control unit responsive to a determination that an interrogation operation is already in progress.