PROVIDING INDIRECT DATA ADDRESSING IN AN INPUT/OUTPUT PROCESSING SYSTEM WHERE THE INDIRECT DATA ADDRESS LIST IS NON-CONTIGUOUS

• US 20090210576A1
• 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., Bendyk, Mark P., Sittmann, Gustav E., Njoku, Ugochukwu C., Casper, Daniel F., Riedy, Dale F.
• Granted Patent: US 7,890,668 B2
• Time in Patent Office: Days
• US Class Current: 710/20
• CPC Class Codes: G06F 12/1009 using page tables, e.g. page table structures
• CPC Class Codes: G06F 12/1036 for multiple virtual address spaces, e.g. segmentation G06F12/1045 takes precedence
• CPC Class Codes: G06F 13/124 where hardware is a sequential transfer control unit, e.g. microprocessor, peripheral processor or state-machine
• CPC Class Codes: G06F 2212/65 Details of virtual memory and virtual address translation
• CPC Class Codes: G06F 3/00 Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/0673 Single storage device

Abstract

Systems, methods and computer program products for providing indirect data addressing at an I/O subsystem of an I/O processing system. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes receiving a control word for an I/O operation. The control word includes an indirect data address for data associated with the I/O operation. The indirect data address includes a starting location of a list of storage addresses that collectively specify the data, the list spans two or more non-contiguous storage locations. Data is gathered responsive to the list. The gathered data is transmitted to a control unit in the I/O processing system.

Claims

1. A computer program product for providing indirect data addressing at an input/output (I/O) subsystem of an I/O processing system, the computer program product comprising:

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

receiving a control word for an I/O operation, the control word including an indirect data address for data associated with the I/O operation, the indirect data address including a starting location of a list of storage addresses that collectively specify the data, the list spanning two or more non-contiguous storage locations;

gathering the data responsive to the list; and

transmitting the gathered data to a control unit in the I/O processing system.

2. The computer program product of claim 1 wherein the list further includes a flag associated with each storage address in the list, the flag having a first value to indicate that the associated storage address refers to a portion of the data and the flag having a second value to indicate that the associated storage address refers to a storage location where additional storage addresses in the list are located.

3. The computer program product of claim 2 wherein for each storage address on the list, the gathering includes:

accessing the storage address and the flag associated with the storage address;

adding contents from the storage address to the data in response to the flag having the first value;

accessing a second storage address and a second flag located at the storage address in response to the flag having the second value, and adding contents from the second storage address to the data in response to the second flag having the first value.

4. The computer program product of claim 2 wherein a second storage address in the list is located contiguously to a first storage address in the list when the flag has the first value, and the second storage address is located non-contiguously to the first storage address when the flag has the second value.

5. The computer program product of claim 1 wherein the list further includes a count field associated with each storage address in the list, the count field indicating a number of bytes to read from the storage address and the gathering is responsive to the count fields and to the storage addresses.

6. The computer program product of claim 1 wherein the control word is a transport control word (TCW), the list of storage addresses is a transport indirect data address list (TIDAL), and each storage address is a transport indirect data address word (TIDAW).

7. The computer program product of claim 1 wherein the I/O subsystem is a channel subsystem.

8. The computer program product of claim 1 wherein the control word includes a flag to indicate that it includes an indirect data address.

9. The computer program product of claim 1 wherein the data includes control data.

10. The computer program product of claim 1 wherein the data includes customer data.

11. An apparatus for providing indirect data addressing at an I/O subsystem of an I/O processing system, the apparatus comprising:

an I/O subsystem adapted to communication with a control unit in the I/O processing system, the I/O subsystem performing a method comprising;

receiving a control word for an I/O operation, the control word including an indirect data address for data associated with the I/O operation, the indirect data address including a starting location of a list of storage addresses that collectively specify the data, the list spanning two or more non-contiguous storage locations;

gathering the data responsive to the list; and

transmitting the gathered data to the control unit.

12. The apparatus of claim 11 wherein the list further includes a flag associated with each storage address in the list, the flag having a first value to indicate that the associated storage address refers to a portion of the data and the flag having a second value to indicate that the associated storage address refers to a storage location where additional storage addresses in the list are located.

13. The apparatus of claim 12 wherein for each storage address on the list, the gathering includes:

accessing the storage address and the flag associated with the storage address;

adding contents from the storage address to the data in response to the flag having the first value;

accessing a second storage address and a second flag located at the storage address in response to the flag having the second value, and adding contents from the second storage address to the data in response to the second flag having the first value.

14. The apparatus of claim 12 wherein a second storage address in the list is located contiguously to a first storage address in the list when the flag has the first value, and the second storage address is located non-contiguously to the first storage address when the flag has the second value.

15. The apparatus of claim 11 wherein the list further includes a count field associated with each storage address in the list, the count field indicating a number of bytes to read from the storage address and the gathering is responsive to the count fields and to the storage addresses.

16. The apparatus of claim 11 wherein the data includes one or both of control data and customer data.

17. The apparatus of claim 11 wherein the I/O subsystem is a channel subsystem that is included in a host system, and an I/O communications adapter in the channel subsystem is adapted to communicate with the control unit via a fibre channel network using a FICON protocol.

18. A method for providing indirect data addressing at an I/O subsystem of an I/O processing system, the method comprising:

receiving a control word for an I/O operation at the I/O subsystem, the control word including an indirect data address for data associated with the I/O operation, the indirect data address including a starting location of a list of storage addresses that collectively specify the data, the list spanning two or more non-contiguous storage locations;

gathering the data responsive to the list;

transmitting the gathered data to a control unit in the I/O processing system.

19. The method of claim 18 wherein the list further includes a flag associated with each storage address in the list, the flag having a first value to indicate that the associated storage address refers to a portion of the data and the flag having a second value to indicate that the associated storage address refers to a storage location where additional storage addresses in the list are located.

20. The method of claim 19 wherein for each storage address on the list, the gathering includes:

accessing the storage address and the flag associated with the storage address;

adding contents from the storage address to the data in response to the flag having the first value;

accessing a second storage address and a second flag located at the storage address in response to the flag having the second value, and adding contents from the second storage address to the data in response to the second flag having the first value.

21. The method of claim 19 wherein a second storage address in the list is located contiguously to a first storage address in the list when the flag has the first value, and the second storage address is located non-contiguously to the first storage address when the flag has the second value.

22. The method of claim 18 wherein the list further includes a count field associated with each storage address in the list, the count field indicating a number of bytes to read from the storage address and the gathering is responsive to the count fields and to the storage addresses.

23. The method of claim 18 wherein the data includes control data.

24. The method of claim 18 wherein the data includes customer data.

25. A computer program product for providing indirect data addressing at an I/O subsystem of an I/O processing system, the computer program product comprising:

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

receiving a control word for an I/O operation, the control word including an indirect data address for customer data output from the I/O operation, the indirect data address including a starting location of a list of storage addresses that collectively specify a storage location for the customer data output, the list spanning two or more non-contiguous storage locations;

receiving the customer data output from a control unit in the I/O processing system in response to the I/O operation being executed at the control unit; and

storing the customer data output at the storage location at the I/O subsystem responsive to the list.