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: A system and method of executing a plurality of threads, including a first thread and a set of remaining threads, on a computer processor core. The system and method includes determining that a start interpretive execution exit condition exists; determining that the computer processor core is within a grace period; and entering by the first thread a start interpretive execution exit sync loop without signaling to any of the set of remaining threads. In turn, the first thread remains in the start interpretive execution exit sync loop until the grace period expires or each of the remaining threads enters a corresponding start interpretive execution exit sync loop.

Abstract: A system and method of executing a plurality of threads, including a first thread and a set of remaining threads, on a computer processor core. The system and method includes determining that a start interpretive execution exit condition exists; determining that the computer processor core is within a grace period; and entering by the first thread a start interpretive execution exit sync loop without signaling to any of the set of remaining threads. In turn, the first thread remains in the start interpretive execution exit sync loop until the grace period expires or each of the remaining threads enters a corresponding start interpretive execution exit sync loop.

Abstract: Selective purging of guest entries of structures associated with address translation. A request to purge entries of a structure associated with address translation is obtained. Based on obtaining the request, a determination is made as to whether selective purging of the structure associated with address translation is to be performed. Based on determining that selective purging is to be performed, one or more entries of the structure associated with address translation are purged. The selectively purging includes clearing the one or more entries of the structure associated with address translation for a selected guest operating system of the computing environment and leaving one or more other entries of one or more other guest operating systems in the structure associated with address translation. The selected guest operating system and the one or more other guest operating systems are managed by a host of the computing environment.

Abstract: A marking capability is used to provide an indication of whether a block of memory is being used by a guest control program to back an address translation structure. The marking capability includes setting an indicator in one or more locations associated with the block of memory. In a further aspect, the marking capability includes an invalidation facility based on the setting of the indicators.

Abstract: An enhanced dynamic address translation facility product is created such that, in one embodiment, a virtual address to be translated and an initial origin address of a translation table of the hierarchy of translation tables are obtained. Dynamic address translation of the virtual address proceeds. In response to a translation interruption having occurred during dynamic address translation, bits are stored in a translation exception qualifier (TXQ) field to indicate that the exception was either a host DAT exception having occurred while running a host program or a host DAT exception having occurred while running a guest program. The TXQ is further capable of indicating that the exception was associated with a host virtual address derived from a guest page frame real address or a guest segment frame absolute address. The TXQ is further capable of indicating that a larger or smaller host frame size is preferred to back a guest frame.

Abstract: According to one aspect, a computer system includes a configuration with a core configurable between a single thread (ST) mode and a multithreading (MT) mode. The ST mode addresses a primary thread, and the MT mode addresses the primary thread and one or more secondary threads. The computer system also includes a multithreading facility configured to control utilization of the configuration to perform a method. Based on determining, by the core in the MT mode, that MT is to be disabled, the MT mode switches to the ST mode, where the primary thread of the MT mode is maintained as the primary thread of the ST mode. A thread context of the one or more secondary threads is made inaccessible to programs. Based on the switching, any one of clearing the program accessible register values or retaining the program accessible register values is performed.

Abstract: According to one aspect, a computer-implemented method for thread context preservation in a configuration including a core configurable between a single thread (ST) mode and a multithreading (MT) mode is provided. The ST mode addresses a primary thread, and the MT mode addresses the primary thread and one or more secondary threads on shared resources of the core. Based on determining, by the core in the MT mode, that MT is to be disabled, switching from the MT mode to the ST mode is performed, where the primary thread of the MT mode is maintained as the primary thread of the ST mode. A thread context including program accessible register values and program counter values of the one or more secondary threads is made inaccessible to programs. Based on the switching, any one of clearing the program accessible register values or retaining the program accessible register values is performed.

Abstract: Management of storage used by pageable guests of a computing environment is facilitated. A query instruction is provided that details information regarding the storage location indicated in the query. It specifies whether the storage location, if protected, is protected by host-level protection or guest-level protection.

Abstract: Management of storage used by pageable guests of a computing environment is facilitated. A query instruction is provided that details information regarding the storage location indicated in the query. It specifies whether the storage location, if protected, is protected by host-level protection or guest-level protection.

Abstract: Embodiments relate to a control area for managing multiple threads in a computer. An aspect is a computer system that includes a virtual machine (VM) configuration with one or more cores. Each core is enabled to operate in a single thread (ST) mode or a multithreading (MT) mode. The ST mode consists of a single thread and the MT mode consists of a plurality of threads on shared resources of a respective core. The computer system includes a core-oriented system control area (COSCA) having a common area representing all of the cores of the VM configuration and separate core description areas for each of the cores in the VM configuration. Each core description area indicates a location of one or more thread description areas each representing a thread within the respective core, and each thread description area indicates a location of a state description of the respective thread.

Abstract: A system and method of implementing a modified priority routing of an input/output (I/O) interruption. The system and method determines whether the I/O interruption is pending for a core and whether any of a plurality of guest threads of the core is enabled for guest thread processing of the interruption in accordance with the determining that the I/O interruption is pending. Further, the system and method determines whether at least one of the plurality of guest threads enabled for guest thread processing is in a wait state and, in accordance with the determining that the at least one of the plurality of guest threads enabled for guest thread processing is in the wait state, routes the I/O interruption to a guest thread enabled for guest thread processing and in the wait state.

Abstract: A measurement sampling facility takes snapshots of the central processing unit (CPU) on which it is executing at specified sampling intervals to collect data relating to tasks executing on the CPU. The collected data is stored in a buffer, and at selected times, an interrupt is provided to remove data from the buffer to enable reuse thereof. The interrupt is not taken after each sample, but in sufficient time to remove the data and minimize data loss.

Abstract: Optimizations are provided for frame management operations, including a clear operation and/or a set storage key operation, requested by pageable guests. The operations are performed, absent host intervention, on frames not resident in host memory. The operations may be specified in an instruction issued by the pageable guests.

Abstract: A measurement sampling facility takes snapshots of the central processing unit (CPU) on which it is executing at specified sampling intervals to collect data relating to tasks executing on the CPU. The collected data is stored in a buffer, and at selected times, an interrupt is provided to remove data from the buffer to enable reuse thereof. The interrupt is not taken after each sample, but in sufficient time to remove the data and minimize data loss.

Abstract: Management of storage used by pageable guests of a computing environment is facilitated. A query instruction is provided that details information regarding the storage location indicated in the query. It specifies whether the storage location, if protected, is protected by host-level protection or guest-level protection.

Abstract: Optimizations are provided for frame management operations, including a clear operation and/or a set storage key operation, requested by pageable guests. The operations are performed, absent host intervention, on frames not resident in host memory. The operations may be specified in an instruction issued by the pageable guests.

Abstract: Embodiments relate to idle time accumulation in a multithreading computer system. According to one aspect, a computer system includes a configuration having a plurality of cores and an operating system (OS)-image configurable between a single thread (ST) mode and a multithreading (MT) mode in a logical partition. The MT mode supports multiple threads on shared resources per core simultaneously. The computer system also includes a multithreading facility configured to perform a method that includes executing a query instruction on an initiating core of the plurality of cores. The executing includes obtaining, by the OS-image, a maximum thread identification value indicating a current maximum thread identifier of the cores within the logical partition. The initiating core also obtains a multithreading idle time value for each of the cores indicating an aggregate amount of idle time of all threads enabled on each of the cores in the MT mode.

Abstract: Embodiments relate to idle time accumulation in a multithreading computer system. According to one aspect, a computer-implemented method for idle time accumulation in a computer system is provided. The computer system includes a configuration having a plurality of cores and an operating system (OS)-image configurable between single thread (ST) mode and a multithreading (MT) mode in a logical partition. The MT mode supports multiple threads on shared resources per core simultaneously. The method includes executing a query instruction on an initiating core of the plurality of cores. The executing includes obtaining, by the OS-image, a maximum thread identification value indicating a current maximum thread identifier of the cores within the logical partition. The initiating core also obtains a multithreading idle time value for each of the cores indicating an aggregate amount of idle time of all threads enabled on each of the cores in the MT mode.

Abstract: Management of storage used by pageable guests of a computing environment is facilitated. A query instruction is provided that details information regarding the storage location indicated in the query. It specifies whether the storage location, if protected, is protected by host-level protection or guest-level protection.