Abstract: Execution of threads in a processor core is controlled. The processor core supports simultaneous multi-threading (SMT) such that there can be effectively multiple logical central processing units (CPUs) operating simultaneously on the same physical processor hardware. Each of these logical CPUs is considered a thread. In such a multi-threading environment, it may be desirous for one thread to stop other threads on the processor core from executing. This may be in response to running a critical sequence or other sequence that needs the processor core resources or is manipulating processor core resources in a way that other threads would interfere with its execution.

Abstract: A processor determines that processing of a thread is suspended due to limited availability of a processing resource. The processor supports execution of the plurality of threads in parallel. The processor obtains a lock on a second processing resource that is substitutable as a resource during processing of the first thread. The second processing resource is included as part of a component that is external to the processor. The component supports a number of threads that is less than the plurality of threads. The processing of the thread is suspended until the lock is available. The processor processes the first thread using the second processing resource. The processor includes a shared register to support mapping a portion of the plurality of threads to the component. The portion of the plurality of threads is equal to, at most, the number of threads supported by component.

Abstract: A mechanism for simultaneous multithreading is provided. Responsive to performing a store instruction for a given thread of threads on a processor core and responsive to the core having ownership of a cache line in a cache, an entry of the store instruction is placed in a given store queue belonging to the given thread. The entry for the store instruction has a starting memory address and an ending memory address on the cache line. The starting memory addresses through ending memory addresses of load queues of the threads are compared on a byte-per-byte basis against the starting through ending memory address of the store instruction. Responsive to one memory address byte in the starting through ending memory addresses in the load queues overlapping with a memory address byte in the starting through ending memory address of the store instruction, the threads having the one memory address byte is flushed.

Abstract: A mechanism for simultaneous multithreading is provided. Responsive to performing a store instruction for a given thread of threads on a processor core and responsive to the core having ownership of a cache line in a cache, an entry of the store instruction is placed in a given store queue belonging to the given thread. The entry for the store instruction has a starting memory address and an ending memory address on the cache line. The starting memory addresses through ending memory addresses of load queues of the threads are compared on a byte-per-byte basis against the starting through ending memory address of the store instruction. Responsive to one memory address byte in the starting through ending memory addresses in the load queues overlapping with a memory address byte in the starting through ending memory address of the store instruction, the threads having the one memory address byte is flushed.

Abstract: Embodiments relate to controlling observability of transactional and non-transactional stores. An aspect includes receiving one or more store instructions. The one or more store instructions are initiated within an active transaction and include store data. The active transaction effectively delays committing stores to memory until successful completion of the active transaction. The store data is stored in a local storage buffer causing alterations to the local storage buffer from a first state to a second state. A signal is received that the active transaction has terminated. If the active transaction has terminated abnormally then: the local storage buffer is reverted back to the first state if the store data was stored by a transactional store instruction, and is propagated to a shared cache if the store instruction is non-transactional.

Abstract: Embodiments relate to a method, system and computer program product for storing a system-absolute address (SAA) in a first level look-aside buffer (TLB). In one embodiment, the system includes a central processor including the TLB and general purpose registers (GPRS). The TLB is configured for storing the SAA. The central processor is configured for issuing a load system-absolute address (LSAA) instruction. The system includes a translation unit that is in communication with the TLB of the central processor. The system is configured to perform a method including determining, based on the LSAA instruction being issued, whether the SAA is stored in the TLB. The method includes sending a translation request to the translation unit from the central processor based on the SAA not being stored in the TLB. The method includes determining the SAA by the translation unit based on receiving the translation request.

Abstract: Fetching a cache line into a plurality of caches of a multilevel cache system. The multilevel cache system includes at least a first cache, a second cache on a next higher level and a memory, the first cache being arranged to hold a subset of information of the second cache, the second cache being arranged to hold a subset of information of a next higher level cache or memory if no higher level cache exists. A fetch request is sent from one cache to the next cache in the multilevel cache system. The cache line is fetched in a particular state into one of the caches, and in another state into at least one of the other caches.

Abstract: A technique is provided for monitoring a value without repeated storage access. A processing circuit processes an instruction of a program that specifies a memory address of a memory location to be monitored. The processing circuit configures a monitor station for monitoring the memory location. The memory location includes a state descriptor for the program. The processing circuit receives a cross-invalidate request from a memory controller. The cross-invalidate request indicates to the monitor station that content of the memory location has been changed by another processing circuit.

Abstract: Embodiments relate to tracking a transactional execution footprint. An aspect includes receiving a store instruction which includes store data. It is determined if the store instruction is executing within a transaction that effectively delays committing stores to a shared cache until the transaction has completed. The store data is stored to a cache line in a local cache. The cache line is marked as dirty if the transaction is active. The stored data that was marked as dirty in the local cache is invalidated if the transaction has terminated abnormally. The stored data is un-marked if it is determined that the transaction has successfully ended.

Abstract: Embodiments relate to collision-based alternate hashing. An aspect includes receiving an incoming instruction address. Another aspect includes determining whether an entry for the incoming instruction address exists in a history table based on a hash of the incoming instruction address. Another aspect includes based on determining that the entry for the incoming instruction address exists in the history table, determining whether the incoming instruction address matches an address tag in the determined entry. Another aspect includes based on determining that the incoming instruction address does not match the address tag in the determined entry, determining whether a collision exists for the incoming instruction address. Another aspect includes based on determining that the collision exists for the incoming instruction address, activating alternate hashing for the incoming instruction address using an alternate hash buffer.

Abstract: Embodiments relate to determining the logical address of a transaction abort. In an embodiment, one or more instructions are received are received from an application. The one or more instructions are executed within a first transaction. The first transaction delays committing stores to memory until it has completed. At least one of the one or more instructions includes a first logical memory address. The first logical memory address corresponds to a first memory address in a memory system. It is determined if the first memory address is equal to a second memory address that is stored in a conflict register. Based on determining that they are equal the first logical memory address is saved as a logical address associated with a cross invalidate (XI) signal at a location available to the application.

Abstract: A technique is provided for monitoring a value without repeated storage access. A processing circuit processes an instruction of a program that specifies a memory address of a memory location to be monitored. The processing circuit configures a monitor station for monitoring the memory location. The memory location includes a state descriptor for the program. The processing circuit receives a cross-invalidate request from a memory controller. The cross-invalidate request indicates to the monitor station that content of the memory location has been changed by another processing circuit.

Abstract: According to an embodiment, a computer system for cache management includes a processor and a cache, the computer system configured to perform a method including receiving a first store request for a first address in the cache and receiving a first fetch request for the first address in the cache. The method also includes executing the first store request and the first fetch request, latching the first store request in a store write-back pipeline in the cache, detecting, in the processor, a conflict following execution of the first store request and the first fetch request and receiving the first store request from a recycle path including the store write-back pipeline and executing the first store request a second time.

Abstract: Embodiments relate to prefetch address translation in a computer processor. An aspect includes issuing, by prefetch logic, a prefetch request comprising a virtual page address. Another aspect includes, based on the prefetch request missing the TLB and the address translation logic of the processor being busy performing a current translation request, comparing a page of the prefetch request to a page of the current translation request. Yet another aspect includes, based on the page of the prefetch request matching the page of the current translation request, storing the prefetch request in a prefetch buffer.

Abstract: Store multiple instructions are managed based on previous execution history and their alignment. At least one store multiple instruction is detected. A flag is determined to be associated with the at least one store multiple instruction. The flag indicates that the at least one store multiple instruction has previously encountered an operand store compare hazard. The at least one store multiple instruction is organized into a set of unit of operations. The set of unit of operations is executed. The executing avoids the operand store compare hazard previously encountered by the at least one store multiple instruction.

Abstract: According to an embodiment, a computer system for cache management includes a processor and a cache, the computer system configured to perform a method including receiving a first store request for a first address in the cache and receiving a first fetch request for the first address in the cache. The method also includes executing the first store request and the first fetch request, latching the first store request in a store write-back pipeline in the cache, detecting, in the processor, a conflict following execution of the first store request and the first fetch request and receiving the first store request from a recycle path including the store write-back pipeline and executing the first store request a second time.

Abstract: A system and method for controlling restarting of instruction fetching using speculative address computations in a processor are provided. The system includes a predicted target queue to hold branch prediction logic (BPL) generated target address values. The system also includes target selection logic including a recycle queue. The target selection logic selects a saved branch target value between a previously speculatively calculated branch target value from the recycle queue and an address value from the predicted target queue. The system further includes a compare block to identify a wrong target in response to a mismatch between the saved branch target value and a current calculated branch target, where instruction fetching is restarted in response to the wrong target.

Abstract: Embodiments relate to a transactional read footprint after a cache line eviction. An aspect includes executing one or more read instructions in an active transaction. A cross invalidate (XI) request for a target cache line is received, and it is determined if the target cache line is part of a congruence class in a local cache. It is further determined whether an extension flag associated with the congruence class is set. The extension flag is used to indicate that cache lines of the congruence class associated with the active transaction have been replaced based only on being least recently used and that the target cache line is not in the cache. Execution of the active transaction continues based on determining that the extension flag is not set. Execution of the active transaction is aborted based on determining that the extension flag is set.

Abstract: Provided are techniques for handling a store buffer in conjunction with a processor, the store buffer comprising a free list; a merge window; and an evict list; and logic, for, upon receipt of a T_STORE operation, comparing a first address associated with the T_STORE operation with a plurality of addresses associated with previous T_STORE operations, wherein the previous T_STORE operations are part of the same transaction as the T_STORE operation and the entries corresponding to the previous T_STORE operations are stored in the merge window; in response to a match between the first address and a second address, associated with a second T_STORE operation, of the plurality of addresses, merging a first entry corresponding to the first T_STORE operation with a second entry corresponding to the second T_STORE operation; and consolidating results associated with the first T_STORE operation with results associated with the second T_STORE operation.

Abstract: A computer program product for mitigating conflicts for shared cache lines between an owning core currently owning a cache line and a requestor core. The computer program product includes a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method. The method includes determining whether the owning core is operating in a transactional or non-transactional mode and setting a hardware-based reject threshold at a first or second value with the owning core determined to be operating in the transactional or non-transactional mode, respectively. The method further includes taking first or second actions to encourage cache line sharing between the owning core and the requestor core in response to a number of rejections of requests by the requestor core reaching the reject threshold set at the first or second value, respectively.