FACILITATING INPUT/OUTPUT PROCESSING BY USING TRANSPORT CONTROL WORDS TO REDUCE INPUT/OUTPUT COMMUNICATIONS

• US 20080147889A1
• Filed: 10/10/2006
• Published: 06/19/2008
• Est. Priority Date: 10/10/2006
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Flanagan, John R., Casper, Daniel F.
• Granted Patent: US 7,500,023 B2
• Time in Patent Office: Days
• US Class Current: 710/5
• CPC Class Codes: G06F 13/126 and has means for transferring I/O instructions and statuses between control unit and main processor

Abstract

Input/output processing is facilitated by reducing communications between input/output communications adapters and control units during input/output processing. The number of exchanges and sequences between an input/output communications adapter and control unit is reduced by sending a plurality of commands from the adapter to the control unit as a single entity for execution by the control unit. The control unit executes the commands and provides the data, if any, in one sequence. The control unit relieves the adapter of the responsibility of tracking state of the individual commands and is able to calculate precise measurement data relating to execution of the commands.

Claims

1. A method of facilitating input/output processing of a processing environment, said method comprising:

obtaining by an input/output communications adapter of the processing environment a transport control word, said transport control word specifying a location in memory of the processing environment that includes a plurality of input/output commands to be executed;

forwarding from the input/output communications adapter to a control unit of the processing environment the plurality of input/output commands as one entity; and

executing by the control unit the plurality of input/output commands to perform one or more input/output operations, wherein the executing is performed absent a tracking by the input/output communications adapter of state relative to the individual input/output commands of the plurality of input/output commands being executed by the control unit.

2. The method of claim 1, wherein the forwarding includes forwarding from the input/output communications adapter to the control unit a descriptor control block, said descriptor control block comprising the plurality of input/output commands to be executed, and wherein the location in memory specified in the transport control word comprises a memory address of the descriptor control block.

3. The method of claim 2, wherein the descriptor control block further comprises a header providing information relating to the input/output commands to be executed and descriptor data for one or more of the input/output commands.

4. The method of claim 3, wherein the descriptor data comprises control data to be provided to a device coupled to the control unit, the device designated by a device address specified in the header of the descriptor control block, said control data being provided to the device absent a separate data transfer.

5. The method of claim 2, further comprising applying a checking code to the descriptor control block to enable the control unit to check validity of the descriptor control block.

6. The method of claim 1, wherein the transport control word further specifies a location in memory that includes data or a list of one or more modified indirect data address words.

7. The method of claim 6, wherein the list of one or more modified indirect data address words comprises a single modified indirect data address word list that describes a plurality of data areas for a plurality of descriptor command words.

8. The method of claim 1, wherein a transfer of data resulting from the execution of the plurality of input/output commands is performed using a single exchange between the input/output communications adapter and the control unit.

9. The method of claim 8, further comprising applying a checking code to the data being transferred to check validity of the transferred data.

10. The method of claim 1, further comprising providing by the control unit to the input/output communications adapter at least one of data and status resulting from execution of the plurality of input/output commands, wherein a transfer of data resulting from the execution of the plurality of input/output commands is performed using three communication sequences between the input/output communications adapter and control unit.

11. The method of claim 10, wherein the number of sequences remains the same, even if the number of input/output commands indicated by the location specified in the transport control word increases.

12. The method of claim 1, wherein the input/output communications adapter comprises a channel, and the plurality of input/output commands comprise a plurality of channel commands specified by one or more channel command words, wherein each channel command word comprises a command code, one or more flags and a count field.

13. A system of facilitating input/output processing of a processing environment, said system comprising:

a transport control word specifying a location in memory of the processing environment that includes a plurality of input/output commands to be executed;

an input/output communications adapter of the processing environment to obtain the transport control word and to forward to a control unit of the processing environment the plurality of input/output commands as one entity; and

the control unit to execute the plurality of input/output commands to perform one or more input/output operations, wherein the executing is performed absent a tracking by the input/output communications adapter of state relative to the individual input/output commands of the plurality of input/output commands being executed by the control unit.

14. The system of claim 13, wherein the input/output communications adapter is to forward to the control unit a descriptor control block, said descriptor control block comprising the plurality of input/output commands to be executed, and wherein the location in memory specified in the transport control word comprises a memory address of the descriptor control block.

15. The system of claim 14, wherein the control unit is further adapted to check a checking code applied to the descriptor control block to verify validity of the descriptor control block.

16. The system of claim 13, wherein the transport control word further specifies a location in memory that includes data or a list of one or more modified indirect data address words and further specifies a location in memory for status information.

17. An article of manufacture comprising:

at least one computer usable medium having computer readable program code logic to facilitate input/output processing of a processing environment, the computer readable program code logic comprising;

obtain logic to obtain by an input/output communications adapter of the processing environment a transport control word specifying a location in memory of the processing environment that includes a plurality of input/output commands to be executed;

send logic to send the transport control word to an input/output communications adapter of the processing environment;

forward logic to forward from the input/output communications adapter to a control unit of the processing environment the plurality of input/output commands as one entity; and

execute logic to execute by the control unit the plurality of input/output commands to perform one or more input/output operations, wherein the executing is performed absent a tracking by the input/output communications adapter of state relative to the individual input/output commands of the plurality of input/output commands being executed by the control unit.

18. The article of manufacture of claim 17, wherein the forward logic includes logic to forward from the input/output communications adapter to the control unit a descriptor control block, said descriptor control block comprising the plurality of input/output commands to be executed, and wherein the location in memory specified in the transport control word comprises a memory address of the descriptor control block.

19. The article of manufacture of claim 18, further comprising apply logic to apply a checking code to the descriptor control block to enable the control unit to check validity of the descriptor control block.

20. The article of manufacture of claim 18, further comprising apply logic to apply a checking code to data being transferred as a result of executing the plurality of input/output commands, the data transfer being performed using a single exchange between the input/output communications adapter and the control unit.