Transactional memory preemption mechanism
Mechanisms for executing a transaction in the data processing system are provided. A transaction checkpoint data structure is generated in internal registers of a processor. The transaction checkpoint data structure stores transaction checkpoint data representing a state of program registers at a time prior to execution of a corresponding transaction. The transaction, which comprises a first portion of code that is to be executed by the processor, is executed. An interrupt of the transaction is received while executing the transaction and, as a result, the transaction checkpoint data is stored to a data structure in a memory of the data processing system. A second portion of code is then executed. A state of the program registers is restored using the data structure in the memory of the data processing system in response to an event occurring causing a switch of execution of the processor back to execution of the transaction.
1. A data processing system, comprising:
a processor; and
a memory coupled to the processor, wherein the processor comprises logic that operates to:
generate a transaction checkpoint data structure in internal registers of the processor, wherein the transaction checkpoint data structure stores transaction checkpoint data representing a state of program registers at a time prior to execution of a corresponding transaction;
execute the transaction, wherein the transaction comprises a first portion of code that is to be executed by the processor;
receive an interrupt of the transaction while executing the transaction;
store the transaction checkpoint data to a data structure in the memory of the data processing system in response to receiving the interrupt;
execute a second portion of code, different than the first portion of code; and
restore a state of the program registers using the data structure in the memory of the data processing system in response to an event occurring causing a switch of execution of the processor back to execution of the transaction, wherein the data structure in the memory is an interrupt context record data structure for a program corresponding to the transaction, and wherein the transaction checkpoint data is stored in a first portion of the interrupt context record data structure, and wherein restoring a state of the program registers using the data structure in the memory of the data processing system comprises:
restoring the program registers to a state corresponding to a state prior to executing the transaction based on the checkpoint data stored in the first portion of the interrupt context record data structure in the memory; and
executing a transaction re-checkpoint instruction to generate a new transaction checkpoint data structure in the internal registers of the processor.
2. The system of claim 1 , wherein the logic further operates to copy state data, identifying a state of the program registers at the time of the interrupt, from the program registers to a second portion of the interrupt context record data structure.
3. The system of claim 2 , wherein restoring a state of the program registers using the data structure in the memory of the data processing system further comprises:
restoring the program registers to a state corresponding to a state when the interrupt was received based on the state data stored in the second portion of the interrupt context record data structure.
4. The system of claim 1 , wherein the logic further operates to:
retrieve a processor mode value from a processor mode register;
determine if the processor mode is a transaction mode; and
perform the operations of storing the transaction checkpoint data, executing the second portion of code, and restoring a state of the program registers only in response to the processor mode being a transaction mode.
5. The system of claim 1 , wherein the logic further operates to:
determine whether the interrupt requires an abort of the transaction; and
restore a state of the program registers to a state prior to execution of the transaction using the transaction checkpoint data structure stored in the internal registers of the processor in response to a determination that the interrupt requires an abort of the transaction.
6. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the compute readable program, when executed on a data processing system having a processor and a memory, causes the data processing system to:
generate a transaction checkpoint data structure in internal registers of the processor, wherein the transaction checkpoint data structure stores transaction checkpoint data representing a state of program registers at a time prior to execution of a corresponding transaction;
execute the transaction, wherein the transaction comprises a first portion of code that is to be executed by the processor;
receive an interrupt of the transaction while executing the transaction;
store the transaction checkpoint data to a data structure in the memory of the data processing system in response to receiving the interrupt;
execute a second portion of code, different than the first portion of code; and
restore a state of the program registers using the data structure in the memory of the data processing system in response to an event occurring causing a switch of execution of the processor back to execution of the transaction, wherein the data structure in the memory is an interrupt context record data structure for a program corresponding to the transaction, and wherein the transaction checkpoint data is stored in a first portion of the interrupt context record data structure, and wherein restoring a state of the program registers using the data structure in the memory of the data processing system comprises:
restoring the program registers to a state corresponding to a state prior to executing the transaction based on the checkpoint data stored in the first portion of the interrupt context record data structure in the memory; and
executing a transaction re-checkpoint instruction to generate a new transaction checkpoint data structure in the internal registers of the processor.
7. The computer program product of claim 6 , wherein the computer readable program further causes the data processing system to copy state data, identifying a state of the program registers at the time of the interrupt, from the program registers to a second portion of the interrupt context record data structure.
8. The computer program product of claim 7 , wherein the computer readable program further causes the data processing system to restore a state of the program registers using the data structure in the memory of the data processing system by:
restoring the program registers to a state corresponding to a state when the interrupt was received based on the slate data stored in the second portion of the interrupt context record data structure.
9. The computer program product of claim 6 , wherein the computer readable program further causes the data processing system to:
retrieve a processor mode value from a processor mode register;
determine if the processor mode is a transaction mode; and
perform the operations of storing the transaction checkpoint data, executing the second portion of code, and restoring a state of the program registers only in response to the processor mode being a transaction mode.
10. The computer program product of claim 6 , wherein the computer readable program further causes the data processing system to:
determine whether the interrupt requires an abort of the transaction; and
restore a state of the program registers to a state prior to execution of the transaction using the transaction checkpoint data structure stored in the internal registers of the processor in response to a determination that the interrupt requires an abort of the transaction.