In a multiprocessing system having a coupling facility, communicating messages between the processors and the coupling facility in either a synchronous operation or an asynchronous operation

• US 5,561,809 A
• Filed: 04/11/1995
• Issued: 10/01/1996
• Est. Priority Date: 03/30/1992
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Williams, Joseph A., Helffrich, Audrey A., Elko, David A., Nick, Jeffrey M., Swanson, Michael D., Moore, Brian B., Isenberg, John F. Jr.
• Primary Examiner(s): Bowler, Alyssa H.
• Assistant Examiner(s): FOLLANSBEE, JOHN A
• Application Number:
  US08/420,893
• Time in Patent Office: 539 Days
• Field of Search: 395/800, 395/650, 395/600, 395/425, 395/727, 395/200.08, 395/445
• US Class Current: 709/213
• CPC Class Codes: G06F 13/122 where hardware performs an I/O function other than control of data transfer
• CPC Class Codes: G06F 15/17 using an input/output type connection, e.g. channel, I/O port
• CPC Class Codes: G06F 15/17375 One dimensional, e.g. linear array, ring

Abstract

A mechanism for communicating messages, each including a command and a response, in a network having central processing complexes (CPCs) and one or more coupling facilities. Each coupling facility has a central processor for executing instructions and a main storage. Messages are sent from a message control block in the main storage of the CPC sending the message, and the response to the message is received in a message response block of the CPC without an interrupt to the program being executed by the central processor of the CPC. Each message from a CPC to the coupling facility may include a command and an indicator bit which instructs the coupling facility to execute the command either in synchronism with or asynchronously to the execution of the sending processor. The coupling facility executes the command and returns a response which is received in a message response block of the main storage of the sending CPC without an interrupt to any program being executed by the central processor of that CPC.

Claims

1. A multiprocessor data processing system comprising:

multiple central processing complexes (CPCs), each CPC having a central processor for executing instructions arranged in programs for processing data, main storage for storing said programs and data including state information for the copy of data in that main storage which is shared between that CPC and at least one other CPC, and subchannel means connected to said main storage for performing message operations;

a structured external storage device for storing state information for data shared between said CPCs;

multiple message paths, each message path having a first end connected to one of said subchannel means and a second end connected to said structured external storage device for passing, during said message operations, data, messages and responses between the connected subchannel means and said structured external storage device;

program means in the main storage of each CPC, respectively, each program means having instructions executed by said central processor of the respective CPC for starting a message operation by said subchannel means of the respective CPC for transferring, during said message operations, data, messages and responses between said main storage of the respective CPC and said structured external storage device in a pipelined fashion wherein, during said message operations, said central processor of the respective CPC is enabled to continue executing instructions Of programs of the respective CPC without an interruption for indicating said message operations are completed;

completion vector means accessible by said subchannel means, said completion vector means having a bit which has a first condition and a second condition;

said program means having means for setting said bit in its first condition when said program means starts a message operation;

said subchannel means having means for resetting said bit to its second condition when said subchannel means completes said message operation; and

said program means includes a completion vector polling means having access to said completion vector means for periodically polling said bit for determining when said bit is in its second condition, thereby indicating said message operation has completed.

2. The data processing system of claim 1 further comprising a program modifiable N bit storage means, the contents of said N bit having a first condition for enabling the use of said completion vector polling means and a second condition for not enabling the use of said completion vector polling means.

3. The data processing system of claim 1 wherein said program means includes means for specifying the completion vector and bit therein to be acted on by said subchannel means when said N bit is in its first condition.

4. The data processing system of claim 1 further comprising;

status means in said subchannel means, said status means having an idle condition when said subchannel is available for performing message operations and an active condition when said subchannel is not available for performing message operations; and

status storage means in said main storage and accessible by said subchannel means, said subchannel means having means for storing the condition of said status means in said status storing means such that said programs are able to determine the status condition of said subchannel means.

5. The data processing system of claim 4 further comprising:

status setting means in said subchannel means connected to said status means, said status setting means for setting the status of said status means to its active condition when a message operation is being performed in said subchannel means such that said subchannel means is not available for message operations.

6. The data processing system of claim 5 further comprising;

test message means in said program means for testing the status information stored in said status means for determining whether said status means is in its active or idle condition.

7. The data processing system of claim 6 further comprising means for over-indicating the active condition of said status means to said test message means in the presence of concurrent serialized accesses to said status means, such that said test message means does not perform serialization or checkpoint-synchronization actions.

8. The data processing system of claim 4 wherein said status setting means includes send message means for setting the status of said status means in its active condition when a message operation is started in said subchannel means by said program means.

9. The data processing system of claim 8 further comprising:

clear message means in said program means for performing a clear function thereby terminating the current message operation at said subchannel, said status setting means having means for setting the status of said status means to its active condition when the said clear function is performed.

10. The data processing system of claim 9 wherein said status setting means includes status pending means for setting the status of said status means to a third, status pending condition when said message operation completes in an other than expected manner, wherein said status pending condition indicates said subchannel means is not available for performing message operations.

11. The data processing system of claim 10 further comprising:

idle status means in said subchannel means connected to said status means, said idle status means for resetting the status of said status means to its idle condition when said data exchange is completed by said subchannel means in an expected manner.

12. The data processing system of claim 11 further comprising:

test message means in said program means for testing the status information stored in said status means for determining if said status means is in one of (1) its active condition as set by said send message means or said clear message means, or (2) its status pending condition as set by said status pending means, or (3) its idle condition as reset by said idle means.

13. The data processing system of claim 11 further comprising serialization means associated with said completion vector means, said status pending means, said idle means and said status means, said serialization means for updating of said bit in said bit vector when said N bit is in its first condition before any status pending or said idle conditions are made in said status means, such that they are concurrently observable to said program.

14. A multiprocessor data processing system comprising:

multiple central processing complexes (CPCs), each CPC having a central processor for executing instructions arranged in programs for processing data, main storage for storing said programs and data including state information for the copy of data in that main storage which is shared between that CPC and at least one other CPC, and subchannel means connected to said main storage for performing message operations for exchanging data, messages and responses with said main storage;

a structured external storage device for storing state information for data shared between said CPCs;

multiple message path, each message path having a first end connected to a different one of said subchannel means and a second end connected to said structured external storage device for passing data, messages and responses between said subchannel means and said structured external storage device;

status means in the subchannel means of each of said CPCs, respectively, said status means having an idle condition when said subchannel of the respective CPC is available for performing message operations and an active condition when said subchannel of the respective CPC is not available for performing message operations;

status testing program means in each of the CPCs, respectively, having instructions executed by said central processor of the respective CPC for testing the condition of the respective status means to determine the status condition of the respective subchannel means thereby determining when a message operation in the respective CPC is completed;

a message control block in said main storage for storing messages to be outputted from said main storage by a send message command executed by said central processor; and

a message response block in said main storage for receiving a response inputted into said main responsive to said send message command.

15. The data processing system of claim 14 wherein each of said CPCs further comprises:

status setting means in said subchannel means connected to said status means, said status setting means for setting the status of said status means to its active condition when a message operation is being performed in said subchannel means such that said subchannel means is not available for message operations.

16. The data processing system of claim 15 further comprising;

test message program means having instructions executed by said central processor for testing the status information stored in said status means for determining whether said status means is in its active or idle condition.

17. The data processing system of claim 15 further comprising means for over-indicating the active condition of said status means to said test message means in the presence of concurrent serialized accesses to said status means, such that said test message means does not perform serialization or checkpoint-synchronization actions.

18. The data processing system of claim 15 wherein said status setting means includes send message means for setting the status of said status means in its active condition when a message operation is started in said subchannel means by said program means.

19. The data processing system of claim 18 further comprising:

clear message means in said program means for performing a clear function thereby terminating the current message operation at said subchannel, said status setting means having means for setting the status of said status means to its active condition when the said clear function is performed.

20. The data processing system of claim 19 wherein said status setting means includes status pending means for setting the status of said status means to a third, status pending condition when said message operation completes in an other than expected manner, wherein said status pending condition indicates said subchannel means is not available for performing message operations.

21. The data processing system of claim 19 further comprising:

idle status means in said subchannel means connected to said status means, said idle status means for resetting the status of said status means to its idle condition when said data exchange is completed by said subchannel means in an expected manner.

22. The data processing system of claim 21 further comprising:

status storage means in said main storage for storing the status information in said status means such that said status information, including one of (1) its active condition as set by said send message means or said clear message means, or (2) its status pending condition as set by said status pending means, or (3) its idle condition as reset by said idle means, is accessible to said programs in said main storage.

23. The data processing system of claim 22 wherein said status storage means is a subchannel information block means in said main storage;

and further comprising;

store subchannel instruction means in said main storage and executable by said central processor for storing the status information of said subchannel, including the status of said status means, in said subchannel information block means.

24. The data processing of claim 22 wherein said status storage means is an interrupt response block in said main storage;

and further comprising;

test subchannel instruction means in said main storage and executable by said central processor for storing the status information of said subchannel, including the status of said status means, in said interrupt response block.

25. A multiprocessor data processing system comprising:

multiple central processing complexes (CPCs), each CPC having a central processor for executing instructions arranged in programs for processing data, said instructions including send message instructions for sending messages, main storage for storing said programs and data including state information for the copy of data in that main storage which is shared between that CPC and at least one other CPC, and subchannel means connected to said main storage for performing message operations;

a structured external storage device for storing state information for data shared between said CPCs;

multiple message paths, each message path having a first end connected to a different subchannel means and a second end connected to said structured external storage device for passing data, messages and responses between said subchannel means and said structured external storage device;

said messages being sent over said message path from one of said central processors to said structured external storage device as a result of said send message instruction, each message having means for including a command to be executed by said structured external storage device, said command for operating on the state information for shared data stored in said structured external device, and a program modifiable A bit having first condition if the command is to be executed synchronously with the central processor sending the message and a second condition if the command is to be executed asynchronously with the central processor sending the message;

completion vector means accessible by said subchannel means, said completion vector means having a completion bit which has a first condition and a second condition;

program means having means for setting said completion bit in its first condition when said program means starts a message operation;

said subchannel means having means for resetting said completion bit to its second condition when said subchannel means completes said message operation; and

said program means includes a completion vector polling means having access to said completion vector means for periodically polling said completion bit for determining when said completion bit is in its second condition, thereby indicating said message operation has completed.

26. The data processing system of claim 25 further comprising a program modifiable N bit storage means, the contents of said N bit having a first condition for enabling the use of said notification vector polling means and a second condition for not enabling the use of said notification vector polling means.

27. The data processing system of claim 25 wherein said program means includes means for specifying the completion vector and bit therein to be acted on by said subchannel means when said N bit is in its first condition.

28. The data processing system of claim 25 further comprising;

status means in said subchannel means, said status means having an idle condition when said subchannel is available for performing message operations and an active condition when said subchannel is not available for performing message operations; and

status storage means in said main storage and accessible by said subchannel means, said subchannel means having means for storing the condition of said status means in said status storing means such that said programs are able to determine the status condition of said subchannel means.

29. The data processing system of claim 28 further comprising:

status setting means in said subchannel means connected to said status means, said status setting means for setting the status of said status means to its active condition when a message operation is being performed in said subchannel means such that said subchannel means is not available for message operations.

30. The data processing system of claim 29 further comprising;

test message means in said program means for testing the status information stored in said status means for determining whether said status means is in its active or idle condition.

31. The data processing system of claim 30 further comprising means for over-indicating the active condition of said status means to said test message means in the presence of concurrent serialized accesses to said status means, such that said test message means does not perform serialization or checkpoint-synchronization actions.

32. The data processing system of claim 28 wherein said status setting means includes send message means for setting the status of said status means in its active condition when a message operation is started in said subchannel means by said program means.

33. The data processing system of claim 32 further comprising:

clear message means in said program means for performing a clear function thereby terminating the current message operation at said subchannel, said status setting means having means for setting the status of said status means to its active condition when the said clear function is performed.

34. The data processing system of claim 33 wherein said status setting means includes status pending means for setting the status of said status means to a third, status pending condition when said message operation completes in an other than expected manner, wherein said status pending condition indicates said subchannel means is not available for performing message operations.

35. The data processing system of claim 34 further comprising:

idle status means in said subchannel means connected to said status means, said idle status means for resetting the status of said status means to its idle condition when said data exchange is completed by said subchannel means in an expected manner.

36. The data processing system of claim 35 further comprising:

test message means in said program means for testing the status information stored in said status means for determining if said status means is in one of (1) its active condition as set by said send message means or said clear message means, or (2) its status pending condition as set by said status pending means, or (3) its idle condition as reset by said idle means.

37. The data processing system of claim 35 further comprising serialization means associated with said completion vector means, said status pending means, said idle means and said status means, said serialization means for updating of said bit in said bit vector when said N bit is in its first condition before any status pending or said idle conditions are made in said status means, such that they are concurrently observable to said programs.

38. The data processing system of claim 28 wherein said status storage means is a subchannel information block means in said main storage;

and further comprising;

store subchannel instruction means in said main storage and executable by said central processor for storing the status information of said subchannel, including the status of said status means, in said subchannel information block means.

39. The data processing of claim 28 wherein said status storage means is an interrupt response block in said main storage;

and further comprising;

test subchannel instruction means in said main storage and executable by said central processor for storing the status information of said subchannel, including the status of said status means, in said interrupt response block.

40. The data processing system of claim 25 wherein each CPC further comprises:

a message control block in said main storage for storing messages to be outputted from said main storage by a send message command executed by said central processor; and

a message response block in said main storage for receiving a response inputted into said main storage responsive to said send message command.

41. A multiprocessor data processing system comprising:

multiple central processing complexes (CPCs), each CPC including

a central processor for executing instructions arranged in programs for processing data,

main storage for storing said programs, operating systems for one or more images, data including data shared between two or more images, and state information for data shared between two or more images in the main storage and shared with other CPCs,

input/output (I/O) subchannel means for performing I/O data transfers,

intersystem (I/S) subchannel means for performing I/S message operations for transferring data, messages and responses,

a message control block in said main storage for storing messages to be outputted from said main storage by a send message command executed by said central processor,

a message response block in said main storage for receiving a response inputted into said main storage responsive to said send message command;

a structured external storing (SES) device for storing state information for data shared between images and CPCs;

multiple message paths, at least one message path between the I/S subchannel means in each of said CPCs and said SES facility;

I/O devices for storing data including said shared data;

multiple I/O paths, each I/O path being between selected ones of said I/O devices and the I/O subchannel means of selected ones of said CPCs;

status means in each of said I/S subchannel means, said status means having an idle condition when its I/S subchannel means is available for performing message operations and an active condition when its I/S subchannel means is not available for performing message operation; and

each CPC includes program means having instructions executed by its central processor for testing the condition of said status means to determine the status condition of its I/S subchannel means thereby determining when a message operation is completed.

42. The data processing system of claim 41 further comprising:

status setting means in each I/S subchannel means connection to said status means, said status setting means for setting the status of said status means to its active condition when a message operation is being performed in its I/S subchannel means such that its I/S subchannel means is not available for message operations.

43. The data processing system of claim 42 further comprising;

test message program means in each CPC having instructions executed by its central processor for testing the status information stored in said status means for determining whether said status means is in its active or idle condition.

44. The data processing system of claim 43 further comprising means for over-indicating the active condition of said status means to said test message means in the presence of concurrent serialized accesses to said status means, such that said test message means does not perform serialization or checkpoint-synchronization actions.

45. The data processing system of claim 42 wherein said status setting means includes send message means for setting the status of said status means in its active condition when a message operation is started in its I/S subchannel means by said program means.

46. The data processing system of claim 45 further comprising:

clear message means in said program means for performing a clear function thereby terminating the current message operation at said subchannel, said status setting means having means for setting the status of said status means to its active condition when the said clear function is performed.

47. The data processing system of claim 46 wherein said status setting means includes status pending means for setting the status of said status means to a third, status pending condition when said message operation completes in an other than expected manner, wherein said status pending condition indicates said subchannel means is not available for performing message operations.

48. The data processing system of claim 47 further comprising:

idle status means in said subchannel means connected to said status means, said idle status means for resetting the status of said status means to its idle condition when said data exchange is completed by said subchannel means in an expected manner.

49. The data processing system of claim 48 further comprising:

status storage means in each main storage for storing the status information in said status means such that said status information, including one of (1) its active condition as by said send message means or said clear message means, or (2) its status pending condition as set by said status pending means, or (3) its idle condition as reset by said idle means, is accessible to said programs in said main storage.

50. The data processing system of claim 49 wherein said status storage means is a subchannel information block means in the respective main storage, and further comprising:

store subchannel instruction means in each CPC and executable by its central processor for storing the status information of the respective I/S subchannel means, including the status of said status means, in said subchannel information block means.

51. The data processing system of claim 49 wherein said status storage means is an interrupt response block in the respective main storage, and further comprising:

test subchannel instruction means each CPC and executable by its central processor for storing the status information of the respective I/S subchannel means, including the status of said status means, in said interrupt response block.

52. A multiprocessor data processing system comprising:

multiple central processing complexes (CPCs), each CPC including

a central processor for executing instructions arranged in programs for processing data,

main storage for storing said programs, operating systems for one or more images, data including data shared between two or more images, and state information for data shared between two or more images in the main storage and shared with other CPC,

input/output (I/O) subchannel means for performing I/O data transfers,

intersystem (I/S) subchannel means for performing I/S message operations for transferring data, messages and responses,

a message control block in said main storage for storing messages to be outputted from said main storage by a send message command executed by said central processor,

a message response block in said main storage for receiving a response inputted into said main storage responsive to said send message command;

a structured external storing (SES) device for storing state information for data shared between images and CPCs;

multiple message paths, at least one message path between the I/S subchannel means in each of said CPCs and said SES facility;

I/O devices for storing data including said shared data;

multiple I/O paths, each I/O path being between selected ones of said I/O devices and the I/O subchannel means of selected ones of said CPCs;

wherein said messages being sent over each message path from an I/S subchannel means to said structured external storage device as a result of a send message instruction, each message having means for including a command to be executed by said structured external storage device, said command for operating on the state information for shared data stored in said structured external device, and a program modifiable A bit having a first condition if the command is to be executed synchronously with the sending central processor and a second condition if the command is to be executed asynchronously with the sending central processor.

53. The data processing system of claim 52 further comprising:

completion vector means in each CPC accessible by its I/S subchannel means, said completion vector means having a bit which has a first condition and a second condition;

the program means of the respective CPC having means for setting said bit in its first condition when the respective program means starts a message operation;

each I/S subchannel means having means for resetting said bit to its second condition when said respective I/S subchannel means completes said message operation; and

the respective program means includes a completion vector polling means having access to said completion vector means for periodically polling said bit for determining when said bit is in its second condition, thereby indicating said message operation has completed.

54. The data processing system of claim 53 further comprising a program modifiable N bit storage means in each CPC, the contents of said N bit having a first condition for enabling the use of said notification vector polling means and a second condition for not enabling the use of said notification vector polling means.

55. The data processing system of claim 54 wherein the program means of each CPC includes means for specifying the completion vector and bit therein to be acted on by the respective I/S subchannel means when its N bit is in its first condition.