Abstract: Hardware assisted transactional memory system with open nested transactions. Some embodiments described herein implement a system whereby hardware acceleration of transactions can be accomplished by implementing open nested transaction in hardware which respect software locks such that a top level transaction can be implemented in software, and thus not be limited by hardware constraints typical when using hardware transactional memory systems.

Abstract: Private or shared read-only memory regions. One embodiment may be practiced in a computing environment including a plurality of agents. A method includes acts for declaring one or more memory regions private to a particular agent or shared read only amongst agents by having software utilize processor level instructions to specify to hardware the private or shared read only memory address regions. The method includes an agent executing a processor level instruction to specify one or more memory regions as private to the agent or shared read-only amongst a plurality of agents. As a result of an agent executing a processor level instruction to specify one or more memory regions as private to the agent or shared read-only amongst a plurality of agents, a hardware component monitoring the one or more memory regions for conflicting accesses or prevents conflicting accesses on the one or more memory regions.

Abstract: Provided is a method, system, and program for coordinating access to memory locations for hardware transactional memory transactions and software transactional memory transactions. A hardware transaction executing in hardware transactional memory initiates a request to access a memory location. A fault is returned to the hardware transaction request in response to an operation by one software transaction executing in a software transactional memory.

Abstract: Object-based conflict detection is described in the context of software transactional memory. In one example, a pointer is received for a block of instructions, the block of instructions having allocated objects. The lower bits of the pointer are masked if the pointer is in a small object space to obtain a block header for the block, and a size of the allocated objects is determined using the block header.

Abstract: A method and apparatus for accelerating transactional execution. Barriers associated with shared memory lines referenced by memory accesses within a transaction are only invoked/executed the first time the shared memory lines are accessed within a transaction. Hardware support, such as a transaction field/transaction bits, are provided to determine if an access is the first access to a shared memory line during a pendancy of a transaction. Additionally, in an aggressive operational mode version numbers representing versions of elements stored in shared memory lines are not stored and validated upon commitment to save on validation costs. Moreover, even in a cautious mode, that stores version numbers to enable validation, validation costs may not be incurred, if eviction of accessed shared memory lines do not occur during execution of the transaction.

Abstract: Methods and apparatus are disclosed to tune intermediate representations in a managed runtime environment. An example method disclosed herein receives a bytecode at a virtual machine during runtime, determines a method of the received bytecode, identifies an optimized intermediate representation associated with the method, and imports the optimized intermediate representation from the memory into the virtual machine. Other embodiments are described and claimed.

Abstract: A method and apparatus for utilizing hardware mechanisms of a transactional memory system is herein described. Various embodiments relate to software-based filtering of operations from read and write barriers and read isolation barriers during transactional execution. Other embodiments relate to software-implemented read barrier processing to accelerate strong atomicity. Other embodiments are also described and claimed.

Abstract: A method and apparatus for optimizing weak atomicity overhead is herein described. A state table is maintained either during static or dynamic compilation of code to track data non-transactionally accessed. Within execution of a transaction, such as at transactional memory accesses or within a commit function, it is determined if data associated with memory access within the transaction is to be conflictingly accessed outside the transaction from the state table. If the data is not accessed outside the transaction, then the transaction potentially commits without weak atomicity safety mechanisms, such as privatization. Furthermore, even if data is accessed outside the transaction, optimized safety mechanisms may be performed to ensure isolation between the potentially conflicting accesses, while eliding the mechanisms for data not accessed outside the transaction.

Abstract: A method and apparatus for optimizing quiescence in a transactional memory system is herein described. Non-ordering transactions, such as read-only transactions, transactions that do not access non-transactional data, and write-buffering hardware transactions, are identified. Quiescence in weak atomicity software transactional memory (STM) systems is optimized through selective application of quiescence. As a result, transactions may be decoupled from dependency on quiescing/waiting on previous non-ordering transaction to increase parallelization and reduce inefficiency based on serialization of transactions.

Abstract: A method and apparatus for unified concurrency control in a Software Transactional Memory (STM) is herein described. A transaction record associated with a memory address referenced by a transactional memory access operation includes optimistic and pessimistic concurrency control fields. Access barriers and other transactional operations/functions are utilized to maintain both fields of the transaction record, appropriately. Consequently, concurrent execution of optimistic and pessimistic transactions is enabled.

Abstract: A method and apparatus for efficiently executing nested transactions is herein described. Hardware support for execution of transactions is provided. Additionally, through the use of logging previous values immediately before a current nested transaction in a local memory and storage of a stack of handlers associated with a hierarchy of transactions, nested transactions are potentially efficiently executed. Upon a failure, abort, or invalidating event/access within a nested transaction, the state of variables or memory locations written to during execution of the nested transaction are rolled-back to immediately before the nested transaction, instead of all the way back to an original state of the variables or memory locations before an enclosing transaction. As a result, nested transactions may be re-executed within enclosing transactions, without flattening the enclosing and nested transactions to re-execute everything.

Abstract: A method and apparatus for accelerating transactional execution. Barriers associated with shared memory lines referenced by memory accesses within a transaction are only invoked/executed the first time the shared memory lines are accessed within a transaction. Hardware support, such as a transaction field/transaction bits, are provided to determine if an access is the first access to a shared memory line during a pendancy of a transaction. Additionally, in an aggressive operational mode version numbers representing versions of elements stored in shared memory lines are not stored and validated upon commitment to save on validation costs. Moreover, even in a cautious mode, that stores version numbers to enable validation, validation costs may not be incurred, if eviction of accessed shared memory lines do not occur during execution of the transaction.

Abstract: A method and apparatus for handling exceptions during execution of a transaction is herein described. A compiler associates a transaction exception handler (TEH) with a transaction in program code, such as through insertion of a call to the TEH. The TEH is also associated with an exception data structure, such as an unwind table, that is utilized during runtime to call an appropriate handler in response to an exception. Additionally, the TEH code is generated by the compiler and inserted into the program code. Upon encountering an exception during execution of the transaction, the TEH is capable of dynamically resizing the transaction to the point of the exception through an attempted commit.

Abstract: Device, system, and method of executing a call to a routine within a transaction. In some embodiments an apparatus may include a memory having stored thereon compiled code corresponding to a transaction, wherein the transaction includes at least one call to a first routine of a pair of first and second mutually inverse routines, and wherein the compiled code includes a call to a first wrapped routine replacing the call to the first routine; and a runtime library including wrapper code, wherein the wrapper code, when executed in response to the call to the first wrapped routine, results in executing the call to the first routine within the transaction and undoing the call to the first routine responsive to abort of the transaction. Other embodiments are described and claimed.

Abstract: A method to perform validation of a read set of a transaction is presented. In one embodiment, the method compares a read signature of a transaction to a plurality of write signatures associated with a plurality of transactions. The method determines based on the result of comparison, whether to update a local value of the transaction to a commit value of another transaction from the plurality of the transactions.

Abstract: A method to perform validation of a read set of a transaction is presented. In one embodiment, the method compares a read signature of a transaction to a plurality of write signatures associated with a plurality of transactions. The method determines based on the result of comparison, whether to update a local value of the transaction to a commit value of another transaction from the plurality of the transactions.

Abstract: Thread synchronization methods and apparatus for managed run-time environments are disclosed.

Abstract: A method and apparatus for hybrid validation for a Software Transaction Memory (STM) is herein described. During execution of a transaction, when acquiring ownership of meta-data associated with a data element, the meta-data is updated with an ownership reference to a transaction to enable efficient subsequent ownership tests. However, during validation, for some conditions, meta-data is updated from the ownership reference to a write entry reference to enable efficient validation.

Abstract: Thread synchronization methods and apparatus for managed run-time environments are disclosed. An example method disclosed herein comprises determining a set of locking operations to perform on a lock corresponding to an object, performing an initial locking operation comprising at least one of a balanced synchronization of the lock and an optimistically balanced synchronization of the lock if the initial locking operation is not unbalanced, and, if the initial locking operation is active and comprises the optimistically balanced synchronization, further comprising modifying a state of a pending optimistically balanced release corresponding to the optimistically balanced synchronization if a subsequent locking operation is unbalanced.

Abstract: According to one embodiment of the invention, a method comprises verifying that a cache block is not exclusively owned, and if not, transmitting a message identifying both the cache block and a caching agent requesting ownership of the cache block to a broadcast interconnect.