I/O command block chain structure in a memory

• US 5,812,877 A
• Filed: 03/15/1996
• Issued: 09/22/1998
• Est. Priority Date: 03/15/1996
• Status: Expired due to Term

• Current Assignee: PMC-Sierra Incorporated (Microchip Technology Incorporated)
• Original Assignee: Adaptec Incorporated (Steel Partners Holdings LP)
• Inventors: Young, B. Arlen
• Primary Examiner(s): Shin, Christopher B.
• Application Number:
  US08/616,846
• Time in Patent Office: 921 Days
• Field of Search: 395/821-827, 395/839-848, 395/852-855, 395/878-881
• US Class Current: 710/24
• CPC Class Codes: G06F 13/126 and has means for transferring I/O instructions and statuses between control unit and main processor

Abstract

An I/O command block, that is stored in a memory, includes information for connecting the I/O command block to other I/O command blocks in a chain structure. Each I/O command block structure in the chain includes a chain control field, a next block pointer, and an offshoot block pointer. The chain control field includes a hold-off field, a concurrent field, an abort field, an aborted field and a progress counter. Upon the hold-off flag having the first state, execution of the I/O command block structure is inhibited. Upon the hold-off flag having the second state, execution of the I/O command block structure is enabled. The concurrent field defines a string of I/O command blocks that are enabled simultaneously for execution. The abort and aborted fields are used to allow one I/O command block to terminate another I/O command block. The progress counter determines when to enable an I/O command block, that is not an offshoot command block, for execution.

Claims

1. An I/O command block chain structure in a memory comprising a plurality of I/O command block structures in said memory wherein each I/O command block structure in said chain comprises:

a chain control field including;

a hold-off flag having first and second states;

wherein upon said hold-off flag having said first state, execution

of said I/O command block structure is inhibited; and

upon said hold-off flag having said second state, execution of

said I/O command block structure is enabled;

a concurrent flag wherein said concurrent flag in each I/O command block structure of a string of concurrent I/O command block structures in said I/O command block chain structure is used to indicate that said string of concurrent I/O command block structures are simultaneously enabled for execution; and

a next block pointer wherein when said I/O command block structure is other than an end of chain I/O command block structure, said next block pointer is a pointer to another I/O command block structure within said I/O command block chain structure, and upon completion of execution of an I/O command in said I/O command block structure, a chain control field of said another I/O command block is analyzed by a chain manager.

2. An I/O command block chain structure in a memory as in claim 1 wherein one of said I/O command block structures in said I/O command block chain structure in said memory is a head of chain I/O command block structure and further wherein said hold-off flag in said chain control field has said second state upon loading said I/O command block chain structure in said memory so that said head of chain I/O command block structure is enabled for execution.

3. An I/O command block chain structure in a memory as in claim 1 wherein one of said I/O command block structures in said I/O command block chain structure in said memory is an end of chain I/O command block structure and said next block pointer in said end of chain I/O command block structure is a pointer to said end of chain I/O command block structure.

4. An I/O command block chain structure in a memory as in claim 1 wherein said chain control field further comprises a progress counter wherein upon said progress counter having a first value, said hold-flag is set to said second state during execution.

5. An I/O command block chain structure in a memory as in claim 1 wherein said concurrent flag has first and second states and concurrent flags in all I/O command block structures in said string, except a last I/O command block structure in said string, have said first state, and a concurrent flag in said last I/O command block structure in said string has said second state.

6. An I/O command block chain structure in a memory as in claim 1 wherein said chain control field further comprises an abort flag and further wherein upon said abort flag being set in a first I/O command block structure, an aborted flag in a chain control field of a second I/O command block structure in said I/O command block chain structure is set during execution.

7. An I/O command block chain structure in a memory as in claim 6 wherein said first I/O command block structure in said chain further comprises:

an offshoot block pointer wherein said second command block is pointed to by said offshoot block pointer.

8. An I/O command block chain structure in a memory as in claim 1 wherein each I/O command block structure in said chain further comprises:

an offshoot block pointer wherein upon completion of execution of an I/O command in a first I/O command block structure, the hold-off flag in a second I/O command block structure pointed to by the offshoot block pointer of said first I/O command block structure is set to said second state.

9. An I/O command block chain structure in a memory comprising a plurality of I/O command block structures in said memory wherein each I/O command block structure in said chain comprises:

a chain control field including;

a hold-off flag having first and second states;

wherein upon said hold-off flag having said first state execution of said I/O command block structure is inhibited; and

upon said hold-off flag having said second state, execution of said I/O command block structure is enabled; and

a progress counter wherein upon said progress counter having a first value, said hold-flag is set to said second state during execution; and

a next block pointer wherein when said I/O command block structure is other than an end of chain I/O command block structure, said next block pointer is a pointer to another I/O command block structure within said I/O command block chain structure, and upon completion of execution of an I/O command in said I/O command block structure, a chain control field of said another I/O command block is analyzed by a chain manager.

10. An I/O command block chain structure in a memory as in claim 9 wherein said chain control field further comprises a concurrent flag, and further wherein said concurrent flag in each I/O command block structure of a string of concurrent I/O command block structures in said I/O command block chain structure is used to indicate that said string of concurrent I/O command block structures are simultaneously enabled for execution.

11. An I/O command block chain structure in a memory as in claim 10 wherein said concurrent flag has first and second states and concurrent flags in all I/O command block structures in said string, except a last I/O command block structure in said string, have said first state, and a concurrent flag in said last I/O command block structure in said string has said second state.

12. An I/O command block chain structure in a memory as in claim 9 wherein said chain control field further comprises an abort flag and further wherein upon said abort flag being set in a first I/O command block structure, an aborted flag in a chain control field of a second I/O command block structure in said I/O command block chain structure is set during execution.

13. An I/O command block chain structure in a memory as in claim 12 wherein said first I/O command block structure in said chain further comprises:

an offshoot block pointer wherein said second command block is pointed to by said offshoot block pointer.

14. An I/O command block chain structure in a memory as in claim 9 wherein each I/O command block structure in said chain further comprises:

an offshoot block pointer wherein upon completion of execution of an I/O command in a first I/O command block structure, the hold-off flag in a second I/O command block structure pointed to by the offshoot block pointer of said first I/O command block structure is set to said second state.

15. An I/O command block chain structure in a memory comprising a plurality of I/O command block structures in said memory wherein each I/O command block structure in said chain comprises:

a chain control field including;

a hold-off flag having first and second states;

wherein upon said hold-off flag having said first state execution of said I/O command block structure is inhibited; and

upon said hold-off flag having said second state, execution of said I/O command block structure is enabled;

a concurrent flag wherein said concurrent flag in each I/O command block structure of a string of concurrent I/O command block structures in said I/O command block chain structure is used to indicate that said string of concurrent I/O command block structures are simultaneously enabled for execution; and

a progress counter wherein upon said progress counter having a first value, said hold-flag is set to said second state during execution; and

a next block pointer wherein when said I/O command block structure is other than an end of chain I/O command block structure, said next block pointer is a pointer to another I/O command block structure within said I/O command block chain structure, and upon completion of execution of an I/O command in said I/O command block structure, a chain control field of said another I/O command block is analyzed by a chain manager.

16. An I/O command block chain structure in a memory as in claim 15 wherein said concurrent flag has first and second states and concurrent flags in all I/O command block structures in said string, except a last I/O command block structure in said string, have said first state, and a concurrent flag in said last I/O command block structure in said string has said second state.

17. An I/O command block chain structure in a memory as in claim 15 wherein said chain control field further comprises an abort flag and further wherein upon said abort flag being set in a first I/O command block structure, an aborted flag in a chain control field of a second I/O command block structure in said I/O command block chain structure is set during execution of said first I/O command block structure.

18. An I/O command block chain structure in a memory as in claim 17 wherein said first I/O command block structure in said chain further comprises:

an offshoot block pointer wherein said second command block is pointed to by said offshoot block pointer.

19. An I/O command block chain structure in a memory as in claim 15 wherein each I/O command block structure in said chain further comprises:

an offshoot block pointer wherein upon completion of execution of an I/O command in a first I/O command block structure, the hold-off flag in a second I/O command block structure pointed to by the offshoot block pointer of said first I/O command block structure is set to said second state.

20. An I/O command block chain structure in a memory comprising a plurality of I/O command block structures in said memory wherein each I/O command block structure in said chain comprises:

a chain control field including;

a hold-off flag having first and second states;

wherein upon said hold-off flag having said first state execution of said I/O command block structure is inhibited; and

upon said hold-off flag having said second state, execution of said I/O command block structure is enabled;

a concurrent flag wherein said concurrent flag in each I/O command block structure of a string of concurrent I/O command block structures in said I/O command block chain structure is used to indicate that said string of concurrent I/O command block structures are simultaneously enabled for execution; and

a progress counter wherein upon said progress counter having a first value, said hold-flag is set to said second state during execution;

a next block pointer wherein when said I/O command block structure is other than an end of chain I/O command block structure, said next block pointer is a pointer to another I/O command block structure within said I/O command block chain structure, and upon completion of execution of an I/O command in said I/O command block structure, a chain control field of said another I/O command block is analyzed by a chain manager; and

an offshoot block pointer wherein upon completion of execution of an I/O command in a first I/O command block structure, the hold-off flag in a second I/O command block structure pointed to by the offshoot block pointer of said first I/O command block structure is set to said second state.