摘要:
A vector compare-and-exchange operation is performed by: decoding by a decoder in a processing device, a single instruction specifying a vector compare-and-exchange operation for a plurality of data elements between a first storage location, a second storage location, and a third storage location; issuing the single instruction for execution by an execution unit in the processing device; and responsive to the execution of the single instruction, comparing data elements from the first storage location to corresponding data elements in the second storage location; and responsive to determining a match exists, replacing the data elements from the first storage location with corresponding data elements from the third storage location.
摘要:
A vector compare-and-exchange operation is performed by: decoding by a decoder in a processing device, a single instruction specifying a vector compare-and-exchange operation for a plurality of data elements between a first storage location, a second storage location, and a third storage location; issuing the single instruction for execution by an execution unit in the processing device; and responsive to the execution of the single instruction, comparing data elements from the first storage location to corresponding data elements in the second storage location; and responsive to determining a match exists, replacing the data elements from the first storage location with corresponding data elements from the third storage location.
摘要:
An apparatus and method is described herein for providing robust speculative code section abort control mechanisms. Hardware is able to track speculative code region abort events, conditions, and/or scenarios, such as an explicit abort instruction, a data conflict, a speculative timer expiration, a disallowed instruction attribute or type, etc. And hardware, firmware, software, or a combination thereof makes an abort determination based on the tracked abort events. As an example, hardware may make an initial abort determination based on one or more predefined events or choose to pass the event information up to a firmware or software handler to make such an abort determination. Upon determining an abort of a speculative code region is to be performed, hardware, firmware, software, or a combination thereof performs the abort, which may include following a fallback path specified by hardware or software. And to enable testing of such a fallback path, in one implementation, hardware provides software a mechanism to always abort speculative code regions.
摘要:
Example methods and apparatus to manage object locks are disclosed. A disclosed example method includes receiving an object lock request from a processor, the lock request associated with object lock code to lock an object, and generating object lock-bypass code based on a type of the processor, the object lock-bypass code to execute in a managed runtime in response to receiving the object lock request. The example method also includes identifying a type of instruction set architecture (ISA) associated with the processor, invoking a checkpoint instruction for the processor based on the identified ISA, suspending the object lock code from executing and executing target code when the object is uncontended, and allowing the object lock code to execute when the object is contended.
摘要:
An apparatus and method is described herein for providing speculative escape instructions. Specifically, an explicit non-transactional load operation is described herein. During execution of a speculative code region (e.g. a transaction or critical section) loads are normally tracked in a read set. However, a programmer or compiler may utilize the explicit non-transactional read to load from a memory address into a destination register, while not adding the read/load to the transactional read set. Similarly, a non-transactional store is also provided. Here, a transactional store is performed and not added to a write set during speculative code execution. And the store may be immediately globally visible and/or persistent (even after an abort of the speculative code region). In other words, speculative escape operations are provided to ‘escape’ a speculative code region to perform non-transactional memory accesses without causing the speculative code region to abort or fail.
摘要:
Methods and apparatus relating to debugging parallel software using speculatively executed code sequences in a multiple core environment are described. In an embodiment, occurrence of a speculative code debug event is detected and a speculative code execution debug module is executed in response to occurrence of the event. Other embodiments are also disclosed and claimed.
摘要:
One embodiment of the present invention provides a system that facilitates avoiding locks by speculatively executing critical sections of code. During operation, the system allows a process to speculatively execute a critical section of code within a program without first acquiring a lock associated with the critical section. If the process subsequently completes the critical section without encountering an interfering data access from another process, the system commits changes made during the speculative execution, and resumes normal non-speculative execution of the program past the critical section. Otherwise, if an interfering data access from another process is encountered during execution of the critical section, the system discards changes made during the speculative execution, and attempts to re-execute the critical section.
摘要:
A method of one aspect may include storing an event count of an event counter that counts events that occur during execution within a logic device. The method may further include restoring the event counter to the stored event count after the event counter has counted additional events. Other methods are also disclosed. Apparatus, systems, and machine-readable medium having software are also disclosed.
摘要:
One embodiment of the present invention provides a system that facilitates avoiding locks by speculatively executing critical sections of code. During operation, the system allows a process to speculatively execute a critical section of code within a program without first acquiring a lock associated with the critical section. If the process subsequently completes the critical section without encountering an interfering data access from another process, the system commits changes made during the speculative execution, and resumes normal non-speculative execution of the program past the critical section. Otherwise, if an interfering data access from another process is encountered during execution of the critical section, the system discards changes made during the speculative execution, and attempts to re-execute the critical section.
摘要:
A method and apparatus for detecting lock instructions and lock release instruction, as well as predicting critical sections is herein described. A lock instruction is detected with detection logic, which potentially resides in decode logic. A lock instruction entry associated with the lock instruction is stored/created. Address locations and values to be written to those address location of subsequent potential lock release instruction are compared to the address loaded from by the lock instruction and the value load by the lock instruction. If the addresses and values match, it is determined that the lock release instruction matches the lock instruction. A prediction entry stores a reference to the lock instruction, such as a last instruction pointer (LIP), and an associated value to represent the lock instruction is to be elided upon subsequent detection, if it is determined that the lock release instruction matches the lock instruction.