Constrained transaction execution

• US 9,740,521 B2
• Filed: 03/03/2013
• Issued: 08/22/2017
• 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, Slegel, Timothy J.
• Primary Examiner(s): Pham, Tuan A
• Application Number:
  US13/783,327
• Publication Number:
  US 20130339967A1
• Time in Patent Office: 1,633 Days
• Field of Search: None
• CPC Class Codes: G06F 9/30076 to perform miscellaneous control operations, e.g. NOP
• CPC Class Codes: G06F 9/3861 Recovery, e.g. branch miss-prediction, exception handling error detection or correction G06F11/00
• CPC Class Codes: G06F 9/467 Transactional memory G06F9/528 takes precedence

Abstract

Constrained transactional processing is provided. A constrained transaction is initiated by execution of a Transaction Begin constrained instruction. The constrained transaction has a number of restrictions associated therewith. Absent violation of a restriction, the constrained transaction is to complete. If an abort condition is encountered, the transaction is re-executed starting at the Transaction Begin instruction. Violation of a restriction may cause an interrupt.

Claims

1. A method of processing transactions within a computing environment, said method comprising:

obtaining, by a processor, a machine instruction, the machine instruction to initiate a transaction of a specified type, the specified type explicitly indicated in a field of the machine instruction;

executing, by the processor, the transaction initiated by the machine instruction, the transaction effectively delaying committing transactional stores to main memory until completion of a selected transaction;

determining, based on executing the transaction, that an abort condition has occurred;

checking whether the specified type of transaction is a constrained transaction, the constrained transaction having one or more restrictions associated therewith, and the checking comprising checking the field of the machine instruction to determine whether the transaction is a constrained transaction; and

performing processing based on determining the abort condition and dependent on the specified type of transaction, wherein based on the checking indicating the transaction is a constrained transaction and based on the abort condition being a particular type of abort condition, the performing processing comprising returning to a beginning of the transaction to re-execute the transaction, and wherein a fail path, other than returning to the beginning of the transaction, is not provided to handle the abort condition.

2. The method of claim 1, wherein the machine instruction comprises a begin transaction instruction, the begin transaction instruction indicating whether the transaction is constrained.

3. The method of claim 2, wherein the returning to the beginning of the transaction comprises returning to the begin transaction instruction.

4. The method of claim 1, further comprising re-executing the transaction, wherein the re-executing comprises performing one or more actions to facilitate completion of the transaction.

5. The method of claim 4, wherein the one or more actions comprise at least one of the following:

inhibiting out-of-order execution;

inhibiting other processors from accessing memory locations conflicting with the transaction;

or

inducing random delays in abort processing.

6. The method of claim 1, wherein the returning to the beginning of the transaction is performed one or more times, prior to completion or interruption of the transaction.

7. The method of claim 1, further comprising:

determining, based on the checking indicating the transaction is a constrained transaction, whether a violation of a restriction of the one or more restrictions has occurred; and

causing an interrupt based on determining the violation has occurred.

8. The method of claim 1, wherein the one or more restrictions comprise at least one of:

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.

9. The method of claim 1, wherein the transaction is to update multiple discontiguous memory locations.

10. The method 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.