Abstract: Disclosed herein is a virtual cache and method in a processor for supporting multiple threads on the same cache line. The processor is configured to support virtual memory and multiple threads. The virtual cache directory includes a plurality of directory entries, each entry is associated with a cache line. Each cache line has a corresponding tag. The tag includes a logical address, an address space identifier, a real address bit indicator, and a per thread validity bit for each thread that accesses the cache line. When a subsequent thread determines that the cache line is valid for that thread the validity bit for that thread is set, while not invalidating any validity bits for other threads.

Abstract: Disclosed herein is a method for operating access to a cache memory via an effective address comprising a tag field and a cache line index field. The method comprises: splitting the tag field into a first group of bits and a second group of bits. The line index bits and the first group of bits are searched in the set directory. A set identifier is generated indicating the set containing the respective cache line of the effective address. The set identifier, the line index bits and the second group of bits are searched in the validation directory. In response to determining the presence of the cache line in the set based on the second searching, a hit signal is generated.

Abstract: Embodiments include load-balancing a plurality of simultaneous threads of a processor. An example method includes computing a minimum group count for a thread from the plurality of threads. The minimum group count indicates a minimum number of groups of instructions to be assigned to the thread. The method further includes computing a maximum allowed group count for the thread. The maximum allowed group count indicates a maximum number of groups of instructions to be assigned to the thread. The method further includes issuing one or more groups of instructions for execution by the thread based on the minimum group count and the maximum allowed group count for the thread.

Abstract: In one example implementation according to aspects of the present disclosure, a computer-implemented method for executing a load instruction with a timeout includes receiving, by a processing device, the load instruction. The method further includes attempting, by the processing device, to load a lock on a cache line of a memory. The method further includes determining, by the processing device, whether the timeout has expired prior to a successful loading of the lock on the cache line. The method further includes , responsive to determining that the timeout has expired, executing, by the processing device, another instruction instead of loading the lock on the cache line.

Abstract: A method of performing instruction scheduling during execution in a processor includes receiving, at an execution unit of the processor, an initial assignment of an assigned execution resource among two or more execution resources to execute an operation. An instruction includes two or more operations. Based on determining that the assigned execution resource is not available, the method also includes determining, at the execution unit, whether another execution resource among the two or more execution resources is available to execute the operation. Based on determining that the other execution resource is available, the method further includes executing the operation with the other execution resource.

Abstract: Disclosed herein is a method for operating access to a cache memory via an effective address comprising a tag field and a cache line index field. The method comprises: splitting the tag field into a first group of bits and a second group of bits. The line index bits and the first group of bits are searched in the set directory. A set identifier is generated indicating the set containing the respective cache line of the effective address. The set identifier, the line index bits and the second group of bits are searched in the validation directory. In response to determining the presence of the cache line in the set based on the second searching, a hit signal is generated.

Abstract: A single architected instruction to move data is executed. The executing includes moving data of a specified length from a source location to a destination location in a right-to-left sequence to provide a predictable result. A predictable result is provided, even though a portion of the destination location is contained within the source location from which the data is being moved.

Abstract: Disclosed herein is a virtual cache and method in a processor for supporting multiple threads on the same cache line. The processor is configured to support virtual memory and multiple threads. The virtual cache directory includes a plurality of directory entries, each entry is associated with a cache line. Each cache line has a corresponding tag. The tag includes a logical address, an address space identifier, a real address bit indicator, and a per thread validity bit for each thread that accesses the cache line. When a subsequent thread determines that the cache line is valid for that thread the validity bit for that thread is set, while not invalidating any validity bits for other threads.

Abstract: Embodiments of the present invention are directed to a computer-implemented method for generating and verifying hardware instruction traces including memory data contents. The method includes initiating an in-memory trace (IMT) data capture for a processor, the IMT data being an instruction trace collected while instructions flow through an execution pipeline of the processor. The method further includes capturing contents of architected registers of the processor by: storing the contents of the architected registers to a predetermined memory location, and causing a load-store unit (LSU) to read contents of the predetermined memory location.

Abstract: A marking capability is used to provide an indication of whether a block of memory is backing an address translation structure of a control program being managed by a virtual machine manager. By providing the marking, the virtual machine manager may check the indication prior to making paging decisions. With this information, a hint may be provided to the hardware to be used in decisions relating to purging associated address translation structures, such as translation look-aside buffer (TLB) entries.

Abstract: Methods, systems and computer program products for dynamically selecting an OSC hazard avoidance mechanism are provided. Aspects include receiving a load instruction that is associated with an operand store compare (OSC) prediction. The OSC prediction is stored in an entry of an OSC history table (OHT) and includes a multiple dependencies indicator (MDI). Responsive to determining the MDI is in a first state, aspects include applying a first OSC hazard avoidance mechanism in relation to the load instruction. Responsive to determining that the load instruction is dependent on more than one store instruction, aspects include placing the MDI in a second state. The MDI being in the second state provides an indication to apply a second OSC hazard avoidance mechanism in relation to the load instruction.

Abstract: Provided are embodiments including a computer-implemented method, system and computer program product for determining precise operand-store-compare (OSC) predictions to avoid false dependencies. Some embodiments include detecting an instruction causing an OSC event, wherein the OSC event is at least one of a store-hit-load event or a load-hit-store event, marking an entry in a queue for the instruction based on the detected OSC event, wherein marking the entry comprises setting a bit and saving a tag in the entry in the queue. Some embodiments also include installing an address for the instruction and the tag in the history table responsive to completing the instruction.

Abstract: A computer implemented method for marking a store instruction overlap in a processor pipeline is provided. A non-limiting example of the method includes detecting a second store instruction subsequent to a first store instruction in an instruction stream, in which there is a match between the operand address information of the first store instruction and a load instruction. The operand address information of the first store instruction is compared with the operand address information of the second store instruction to determine whether there is match. In the event of a match, the second store instruction is delayed in the processor pipeline in response to determining that there is a memory image overlap between the operand address information of the second store instruction and the first store instruction.

Abstract: A single architected instruction to move data is executed. The executing includes moving data of a specified length from a source location to a destination location in a right-to-left sequence to provide a predictable result. A predictable result is provided, even though a portion of the destination location is contained within the source location from which the data is being moved.

Abstract: A system includes a hierarchical metadata predictor and a processing circuit. The hierarchical metadata predictor includes a first-level metadata predictor and a second-level metadata predictor. The processing circuit is configured to perform a plurality of operations including storing new or updated metadata into the first-level metadata predictor and searching the first-level metadata predictor for a metadata prediction. Responsive to finding the metadata prediction in the first-level metadata predictor, the metadata prediction is output corresponding to an entry of the first-level metadata predictor that is a hit. One or more entries of the first-level metadata predictor that are non-hits are periodically written to the second-level metadata predictor. The first-level metadata predictor is updated based on locating the metadata prediction in the second-level metadata predictor.

Abstract: A computer implemented method for saving cache access power is suggested. The cache is provided with a set predictor logic for providing a generated set selection for selecting a set in the cache, and with a set predictor cache for pre-caching generated set indices of the cache. The method comprises further: receiving a part of a requested memory address; checking, in the set predictor cache, whether the requested memory address is already generated; in the case, that the requested memory address has already been generated: securing that the set predictor cache is switched off; issuing the pre-cached generated set index towards the cache; and securing that only that part of the cache is switched on that is associated with the pre-cached generated set index.

Abstract: A guarded storage facility sets up a boundary indicating a range of addresses to be guarded or protected. When a program attempts to access an address in a guarded section defined by the boundary, a guarded storage event occurs. Use of this facility facilitates performance of certain tasks within a computing environment, including storage reclamation.

Abstract: A guarded storage facility sets up a boundary indicating a range of addresses to be guarded or protected. When a program attempts to access an address in a guarded section defined by the boundary, a guarded storage event occurs. Use of this facility facilitates performance of certain tasks within a computing environment, including storage reclamation.

Abstract: An instruction to perform a conditional branch to an indirectly specified location is executed. A branch address is obtained from a location in memory, the location in memory designated by the instruction. A determination is made, based on a condition code of another instruction, whether a branch is to occur, and a branch to the branch address is performed, based on determining the branch is to occur.

Abstract: Disclosed herein is a method for operating access to a cache memory via an effective address comprising a tag field and a cache line index field. The method comprises: splitting the tag field into a first group of bits and a second group of bits. The line index bits and the first group of bits are searched in the set directory. A set identifier is generated indicating the set containing the respective cache line of the effective address. The set identifier, the line index bits and the second group of bits are searched in the validation directory. In response to determining the presence of the cache line in the set based on the second searching, a hit signal is generated.