Transaction begin/end instructions

• US 9,348,642 B2
• Filed: 06/15/2012
• Issued: 05/24/2016
• Est. Priority Date: 06/15/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Greiner, Dan F., Jacobi, Christian, Mitran, Marcel, Slegel, Timothy J.
• Primary Examiner(s): Pham, Tuan A
• Application Number:
  US13/524,845
• Publication Number:
  US 20130339326A1
• Time in Patent Office: 1,439 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 9/30025 Format conversion instructions, e.g. Floating-Point to Integer, decimal conversion
• CPC Class Codes: G06F 9/3004 to perform operations on memory
• CPC Class Codes: G06F 9/30087 Synchronisation or serialisation instructions
• CPC Class Codes: G06F 9/3834 Maintaining memory consistency
• CPC Class Codes: G06F 9/38585 with result invalidation, e.g. nullification
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects
• CPC Class Codes: G06F 9/467 Transactional memory G06F9/528 takes precedence
• CPC Class Codes: G06F 9/5077 Logical partitioning of resources; Management or configuration of virtualized resources specific details on emulation or internal functioning of virtual machines G06F9/455
• CPC Class Codes: G06F 9/528 by using speculative mechanisms

Abstract

A TRANSACTION BEGIN instruction and a TRANSACTION END instruction are provided. The TRANSACTION BEGIN instruction causes either a constrained or nonconstrained transaction to be initiated, depending on a field of the instruction. A constrained transaction has one or more restrictions associated therewith, while a nonconstrained transaction is not limited in the manner of a constrained transaction. The TRANSACTION END instruction ends the transaction started by the TRANSACTION BEGIN instruction.

Claims

1. A computer program product for executing a machine instruction in a computing environment, the machine instruction for initiating a transaction, wherein stores by other processors to storage locations of the transaction cause the transaction to abort, and wherein stores by instructions in the transaction are effectively delayed until a selected transaction completes, said computer program product comprising:

a non-transitory computer readable storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising;

obtaining, by a processor, a machine instruction for operation, the machine instruction being defined for computer execution according to a computer architecture, the machine instruction comprising;

an operation code to specify a transaction begin operation; and

a control field to specify one or more controls to be used in transactional execution; and

executing, by the processor, the machine instruction, the executing comprising;

determining from a field of the instruction whether a transaction to be initiated by the transaction begin instruction is a constrained transaction or a nonconstrained transaction;

based on the field being one value, initiating a constrained transaction, and setting a condition code to a value indicating successful execution of the machine instruction, said constrained transaction having one or more restrictions associated therewith, the one or more restrictions including at least one of a subset of general instructions is available, a limited number of instructions is to be executed, a limited number of storage-operand locations is to be accessed, or the constrained transaction is limited to a single nesting level;

based on the field being another value, designating a storage location for storing diagnostic information in an aborted nonconstrained transaction, initiating the nonconstrained transaction, and setting a condition code to the value indicating successful execution of the machine instruction; and

wherein the field indicates a nonconstrained transaction, and wherein the machine instruction further comprises a base field to be used in executing the transaction, and wherein based on the base field comprising one value, contents of a register specified by the base field are combined with contents of a displacement field to create a first operand address, the first operand address designating a location of a transaction diagnostic block usable to store the diagnostic information on an abort.

2. The computer program product of claim 1, wherein the field comprises the operation code.

3. The computer program product of claim 1, wherein the control field comprises one or more of the following:

a general register save mask to indicate one or more pairs of registers to be saved at a beginning of the transaction and restored on an abort; and

an allow access register modification field to control whether the transaction is allowed to modify an access register.

4. The computer program product of claim 3, wherein the field indicates a nonconstrained transaction, and wherein the control field further comprises:

an allow floating point operation field to control whether the transaction is allowed to execute specified floating point instructions; and

a program interruption filtering control field to control whether certain classes of program interruption conditions result in an interruption.

5. The computer program product of claim 1, wherein the one or more restrictions comprise:

a limited number of instructions within the transaction;

instructions within the transaction are to be within a pre-defined area of memory;

certain pre-specified instructions can be included within the transaction, others are restricted;

a limit on access by storage operands of the transaction;

the transaction does not access storage operands in blocks of memory that contain the pre-defined area of memory;

the transaction does not access instructions or storage operands using different logical addresses mapped to a same absolute address; and

operand references made by the transaction are to be within a specified size.

6. The computer program product of claim 1, wherein the method further comprises:

executing another machine instruction to end the transaction initiated by the transaction begin instruction, the another machine instruction comprising a transaction end instruction, the transaction end instruction comprising an operation code to indicate the transaction end instruction.

7. The computer program product of claim 6, wherein the executing the another machine instruction comprises:

decrementing a transactional nesting depth;

determining whether the decremented transactional nesting depth is zero; and

committing store accesses made by the transaction based on the decremented transactional nesting depth being zero.

8. A computer system for executing a machine instruction in a computing environment, the machine instruction for initiating a transaction, wherein stores by other processors to storage locations of the transaction cause the transaction to abort, and wherein stores by instructions in the transaction are effectively delayed until a selected transaction completes, said computer system comprising:

a memory; and

a processor in communications with the memory, wherein the computer system is configured to perform a method, said method comprising;

obtaining, by a processor, a machine instruction for execution, the machine instruction being defined for computer execution according to a computer architecture, the machine instruction comprising;

an operation code to specify a transaction begin operation; and

a control field to specify one or more controls to be used in transactional execution; and

executing, by the processor, the machine instruction, the executing comprising;

determining from a field of the instruction whether a transaction to be initiated by the transaction begin instruction is a constrained transaction or a nonconstrained transaction;

based on the field being one value, initiating a constrained transaction, and setting a condition code to a value indicating successful execution of the machine instruction, said constrained transaction having one or more restrictions associated therewith, the one or more restrictions including at least one of a subset of general instructions is available, a limited number of instructions is to be executed, a limited number of storage-operand locations is to be accessed, or the constrained transaction is limited to a single nesting level;

based on the field being another value, designating a storage location for storing diagnostic information in an aborted nonconstrained transaction, initiating the nonconstrained transaction, and setting a condition code to the value indicating successful execution of the machine instruction; and

wherein the field indicates a nonconstrained transaction, and wherein the machine instruction further comprises a base field to be used in executing the transaction, and wherein based on the base field comprising one value, contents of a register specified by the base field are combined with contents of a displacement field to create a first operand address, the first operand address designating a location of a transaction diagnostic block usable to store the diagnostic information on an abort.

9. The computer system of claim 8, wherein the field comprises one of:

the operation code or a field of the instruction separate from the operation code.

10. The computer system of claim 8, wherein the control field comprises one or more of the following:

a general register save mask to indicate one or more pairs of registers to be saved at a beginning of the transaction and restored on an abort; and

an allow access register modification field to control whether the transaction is allowed to modify an access register.

11. The computer system of claim 10, wherein the field indicates a nonconstrained transaction, and wherein the control field further comprises:

an allow floating point operation field to control whether the transaction is allowed to execute specified floating point instructions; and

a program interruption filtering control field to control whether certain classes of program interruption conditions result in an interruption.

12. The computer system of claim 8, wherein the method further comprises:

executing another machine instruction to end the transaction initiated by the transaction begin instruction, the another machine instruction comprising a transaction end instruction, the transaction end instruction comprising an operation code to indicate the transaction end instruction.

13. The computer system of claim 12, wherein the executing the another machine instruction comprises:

decrementing a transactional nesting depth;

determining whether the decremented transactional nesting depth is zero; and

committing store accesses made by the transaction based on the decremented transactional nesting depth being zero.

14. The computer system of claim 8, wherein the one or more restrictions comprise:

a limited number of instructions within the transaction;

instructions within the transaction are to be within a pre-defined area of memory;

certain pre-specified instructions can be included within the transaction, others are restricted;

a limit on access by storage operands of the transaction;

the transaction does not access storage operands in blocks of memory that contain the pre-defined area of memory;

the transaction does not access instructions or storage operands using different logical addresses mapped to a same absolute address; and

operand references made by the transaction are to be within a specified size.