In a distributed system where a client's call to commit a transaction occurs outside the transaction's lock-hold interval, computation of timestamp information for the transaction is moved to a client library, while ensuring that no conflicting reads or writes are performed between a time of the computation and acquiring all locks for the transaction. The transaction is committed in phases, with each phase being initiated by the client library. Timestamp information is added to the locks to ensure that timestamps are generated during lock-hold intervals. An increased number of network messages is thereby overlapped with a commit wait period in which a write in a distributed database is delayed in time to ensure concurrency in the database.

A processor configured to manage a transaction memory (TM) state. The processor is configured to receive a first instruction indicating a start of a speculative transaction and update a register file with a speculative transaction memory (TM) state corresponding to the speculative transaction. The processor is further configured to determine whether or not the register file is able to store the entirety of speculative TM state. If the register file is unable to store the entirety of the speculative TM state, the processor is configured to copy a previous TM (pre-TM) state from the register file to a memory which is external to the processor. Further, the processor may be configured to complete updating the register file with the speculative TM state after the pre-TM state has been copied from the register file to the memory.

Systems and methods are disclosed for supporting debugging of programs in block-based processor architectures. In one example of the disclosed technology, a processor includes a block-based processor core for executing an instruction block comprising an instruction header and a plurality of instructions. The block-based processor core includes execution control logic and core state access logic. The execution control logic can be configured to schedule respective instructions of the plurality of instructions for execution in a dynamic order during a default execution mode and to schedule the respective instructions for execution in a static order during a debug mode. The core state access logic can be configured to read intermediate states of the block-based processor core and to provide the intermediate states outside of the block-based processor core during the debug mode.

An apparatus and method are provided for handling prediction information. The apparatus has processing circuitry for performing data processing operations in response to instructions, the processing circuitry comprising transactional memory support circuitry to support execution of a transaction comprising a sequence of instructions. Prediction circuitry is used to generate predictions in relation to instruction flow changing instructions, and prediction storage is provided to store a plurality of items of prediction information that are referenced by the prediction circuitry when generating the predictions. The items of prediction information maintained by the prediction storage change based on the instructions being executed by the processing circuitry. A recovery storage is activated by the transactional memory support circuitry at a transaction start point to store a restore pointer identifying a chosen location in the prediction storage. Between the transaction start point and the transaction end point, the recovery storage receives any item of prediction information removed from the prediction storage that was present in the prediction storage at the transaction start point. In response to the transaction being aborted, the restore pointer is used in order to discard from the prediction storage any items of prediction information added to the prediction storage after the transaction start point, and in addition any items of prediction information stored in the recovery storage are stored back into the prediction storage. This can significantly improve prediction accuracy in systems that may need to retry transactions due to a transaction abort, without requiring the entire prediction storage state to be captured at the transaction start point.

Systems, apparatuses, and methods related to a block-based processor core topology register are disclosed. In one example of the disclosed technology, a processor can include a plurality of block-based processor cores for executing a program including a plurality of instruction blocks. A respective block-based processor core can include a sharable resource and a programmable composition topology register. The programmable composition topology register can be used to assign a group of the physical processor cores that share the sharable resource.

In an apparatus (2) with transactional memory support, a predetermined type of transaction start instruction or a subsequent instruction following the predetermined type of transaction start instruction triggers capture of a lock identifier which identifies a lock variable for controlling exclusive access to at least one resource. In response to a predetermined type of transaction end instruction which follows the predetermined type of transaction start instruction, the lock variable is checked and commitment of results of speculatively executed instructions of the transaction is prevented or deferred when the lock variable indicates that another thread holds the exclusive access to the target resource. This approach can improve performance when executing transactions in a transactional memory based system.

Operating a data distribution including a data distribution module and a plurality of host-bus adapters coupled to the data distribution module can include defining a coherent group that includes a set of members that includes the plurality of host-bus adapters; providing a group-coherent memory area in each of the set of members; and initiating a one-to-all broadcast message from a one of the plurality of host-bus adapters to all of the set of members when the one of the plurality of host-bus adapters requests a write to its local group-coherent memory area. The group-coherent memory area in each of the set of members is physically mirrored with a temporal coherence and no semaphores or access enables are required to achieve the temporal coherence of the coherent group.

A transactional memory system determines whether a hardware transaction can be salvaged. A processor of the transactional memory system begins execution of a transaction in a transactional memory environment. Based on detection that an amount of available resource for transactional execution is below a predetermined threshold level, the processor determines whether the transaction can be salvaged. Based on determining that the transaction can not be salvaged, the processor aborts the transaction. Based on determining the transaction can be salvaged, the processor performs a salvage operation, wherein the salvage operation comprises one or more of: determining that the transaction can be brought to a stable state without exceeding the amount of available resource for transactional execution, and bringing the transaction to a stable state; and determining that a resource can be made available, and making the resource available.

Systems and methods for speculative execution of commands using a controller memory buffer are disclosed. Non-Volatile Memory Express (NVMe) implements a paired submission queue and completion queue mechanism, with host software on a host device placing commands into the submission queue and thereafter notifying a memory device of the commands placed in the submission queue. The submission queue may be resident in the memory device, such as in the controller buffer memory. Prior to notice by the host device, the memory device may determine that the commands have been placed in the submission queue and may speculatively execute the commands. Determining whether to begin processing a command prior to the host device notifying the memory device that the command is posted to the submission queue may be based on a type of command, such as a read or write command. The host device may override a command, such as a flush command, posted to the submission queue, and processing of the command canceled.

Technology related to prefetching instruction blocks is disclosed. In one example of the disclosed technology, a processor comprises a block-based processor core for executing a program comprising a plurality of instruction blocks. The block-based processor core can include prefetch logic and a local buffer. The prefetch logic can be configured to receive a reference to a predicted instruction block and to determine a mapping of the predicted instruction block to one or more lines. The local buffer can be configured to selectively store portions of the predicted instruction block and to provide the stored portions of the predicted instruction block when control of the program passes along a predicted execution path to the predicted instruction block.