Abstract: Mechanisms for building approximate data dependences using a moving look-back window are provided. The mechanisms track dependence information for memory accesses over iterations of execution of a portion of code. The mechanisms receive a memory access of an iteration of the portion of code, the memory access having an address for access the memory and an access type indicating at least one of a read or a write access type. An entry in a moving look-back window data structure is generated corresponding to a memory location accessed by the memory access. The entry comprises at least an identification of the address, the access type, and an iteration number corresponding to the iteration of the memory access. The moving look-back window data structure is utilized to determine dependence information for memory accesses over a plurality of iterations of the portion of code.

Abstract: In an embodiment, if a self thread has more than one conflict, a transaction of the self thread is aborted and restarted. If the self thread has only one conflict and an enemy thread of the self thread has more than one conflict, the transaction of the self thread is committed. If the self thread only conflicts with the enemy thread and the enemy thread only conflicts with the self thread and the self thread has a key that has a higher priority than a key of the enemy thread, the transaction of the self thread is committed. If the self thread only conflicts with the enemy thread, the enemy thread only conflicts with the self thread, and the self thread has a key that has a lower priority than the key of the enemy thread, the transaction of the self thread is aborted.

Abstract: In an embodiment, asynchronous conflict events are received during a previous rollback period. Each of the asynchronous conflict events represent conflicts encountered by speculative execution of a first plurality of work units and may be received out-of-order. During a current rollback period, a first work unit is determined whose speculative execution raised one of the asynchronous conflict events, and the first work unit is older than all other of the first plurality of work units. A second plurality of work units are determined, whose ages are equal to or older than the first work unit, wherein each of the second plurality of work units are assigned to respective executing threads. Rollbacks of the second plurality of work units are performed. After the rollbacks of the second plurality of work units are performed, speculative executions of the second plurality of work units are initiated in age order, from oldest to youngest.

Abstract: An optimizing compiler device, a method, a computer program product which are capable of performing parallelization of irregular reductions. The method for performing parallelization of irregular reductions includes receiving, at a compiler, a program and selecting, at compile time, at least one unit of work (UW) from the program, each UW configured to operate on at least one reduction operation, where at least one reduction operation in the UW operates on a reduction variable whose address is determinable when running the program at a run-time. At run time, for each successive current UW, a list of reduction operations accessed by that unit of work is recorded. Further, it is determined at run time whether reduction operations accessed by a current UW conflict with any reduction operations recorded as having been accessed by prior selected units of work, and assigning the unit of work as a conflict free unit of work (CFUW) when no conflicts are found.

Abstract: Mechanisms are provided for tracking dependencies of threads in a multi-threaded computer program execution. The mechanisms detect a dependency of a first thread's execution on results of a second thread's execution in an execution flow of the multi-threaded computer program. The mechanisms further store, in a hardware thread dependency vector storage associated with the first thread's execution, an identifier of the dependency by setting at least one bit in the hardware thread dependency vector storage corresponding to the second thread. Moreover, the mechanisms schedule tasks performed by the multi-threaded computer program based on the hardware thread dependency vector storage to minimize squashing of threads.

Abstract: Mechanisms are provided for controlling version pressure on a speculative versioning cache. Raw version pressure data is collected based on one or more threads accessing cache lines of the speculative versioning cache. One or more statistical measures of version pressure are generated based on the collected raw version pressure data. A determination is made as to whether one or more modifications to an operation of a data processing system are to be performed based on the one or more statistical measures of version pressure, the one or more modifications affecting version pressure exerted on the speculative versioning cache. An operation of the data processing system is modified based on the one or more determined modifications, in response to a determination that one or more modifications to the operation of the data processing system are to be performed, to affect the version pressure exerted on the speculative versioning cache.

Abstract: A method for executing an atomic transaction includes receiving the atomic transaction at a processor for execution, determining a transactional memory location needed in memory for the atomic transaction, reserving the transactional memory location while all computation and store operations of the atomic transaction are deferred, and performing the computation and store operations, wherein the atomic transaction cannot be aborted after the reservation, and further wherein the store operation is directly committed to the memory without being buffered.

Abstract: A runtime dependence-aware scheduling of dependent iterations mechanism is provided. Computation is performed for one or more iterations of computer executable code by a main thread. Dependence information is determined for a plurality of memory accesses within the computer executable code using modified executable code using a set of dependence threads. Using the dependence information, a determination is made as to whether a subset of a set of uncompleted iterations in the plurality of iterations is capable of being executed ahead-of-time by the one or more available threads in the data processing system. If the subset of the set of uncompleted iterations in the plurality of iterations is capable of being executed ahead-of-time, the main thread is signaled to skip the subset of the set of uncompleted iterations and the set of assist threads is signaled to execute the subset of the set of uncompleted iterations.

Abstract: Computer implemented method, system and computer usable program code for profiling the execution of an application that is both space- and time-efficient and highly accurate. A computer implemented method for profiling the execution of an application includes sampling execution characteristics of the application at a plurality of sampling points to provide samples, and deriving a calling context of the samples. The application is continuously executed between sampling points while additional profiling data is gathered.

Abstract: A method for executing an atomic transaction includes receiving the atomic transaction at a processor for execution, determining a transactional memory location needed in memory for the atomic transaction, reserving the transactional memory location while all computation and store operations of the atomic transaction are deferred, and performing the computation and store operations, wherein the atomic transaction cannot be aborted after the reservation, and further wherein the store operation is directly committed to the memory without being buffered.

Abstract: Computer implemented method, system and computer usable program code for profiling the execution of an application that is both space-and time-efficient and highly accurate. A computer implemented method for profiling the execution of an application includes sampling execution characteristics of the application at a plurality of sampling points to provide samples, and deriving a calling context of the samples. The application is continuously executed between sampling points while additional profiling data is gathered.

Abstract: Computer implemented method, system and computer usable program code for profiling the execution of an application that is both space-and time-efficient and highly accurate. A computer implemented method for profiling the execution of an application includes sampling execution characteristics of the application at a plurality of sampling points to provide samples, and deriving a calling context of the samples. The application is continuously executed between sampling points while additional profiling data is gathered.