Abstract: Input/output interruptions are managed in computing environments that do not use dedicated per-guest interruption hardware to present interruptions. Dispatchable guest programs in the environment receive I/O interruptions directly without hypervisor intervention. This is facilitated by using one or more interruption controls stored in memory and associated with each guest program. For those guest programs that are not currently dispatchable, interruptions can be posted for the guests and notifications to the hypervisor can be aggregated. The hypervisor can then process a plurality of notifications for the plurality of guests in a single invocation.

Abstract: Disclosed are a method and system of tracking real time use of I/O control blocks on a processing unit basis, in a multiprocessing system, such that in the case of a processing unit failure, a list accurately and concisely identifies the control blocks that need to be recovered. This eliminates the need to scan all the I/O control blocks, greatly reducing the overall system recovery time and minimizing impact to the rest of the running system. The preferred embodiment of the invention uses a task control block structure to record which I/O control blocks are in use by each Processing Unit. Also, the lock word structure defined in the I/O control blocks is provided with an index back into the task control block to facilitate managing the task control block entries.

Abstract: Disclosed are a method and system that use state tracking constructs along with additional constructs to identify and recover control blocks inadvertently left locked that caused a hang condition in a multi-processing computing system. The preferred embodiment of the invention uses a task control blocks (TCBs) for processing units (PUs) undergoing channel subsystem (CSS) recovery. (Recovering TCBs for Recovering PUs).

Abstract: Disclosed are a method and system for detecting errors in a computer system including a processing unit to perform tasks to change items. The method comprises the steps of assigning a task control block to the processing unit, and using the task control block to keep track of items being changed by the processing unit. The method comprises the further steps of at defined times, checking the task control block to identify items being changed by the processing unit, and checking the states of said identified items to determine if those states are correct. The preferred embodiment of the invention detects an error when it arises (where possible), and utilizes an infrastructure that allows simple and periodic consistency checks (for example, at designated code points) that detect the error before it causes follow-on problems.

Abstract: Input/output interruptions are managed in computing environments that do not use dedicated per-guest interruption hardware to present interruptions. Dispatchable guest programs in the environment receive I/O interruptions directly without hypervisor intervention. This is facilitated by using one or more interruption controls stored in memory and associated with each guest program. For those guest programs that are not currently dispatchable, interruptions can be posted for the guests and notifications to the hypervisor can be aggregated. The hypervisor can then process a plurality of notifications for the plurality of guests in a single invocation.

Abstract: Input/output (I/O) operation requests from pageable storage mode guests are interpreted without host intervention. In a pageable mode virtual environment, requests issued by pageable storage mode guests are processed by one or more processors of the environment absent intervention from one or more hosts of the environment. Processing of the requests includes manipulating, by at least one processor on behalf of the guests, buffer state information stored in host storage. The manipulating is performed via instructions initiated by the guests and processed by one or more of the processors.

Abstract: Host page management assist functions are employed to manage storage of a pageable mode virtual environment. These functions enable storage to be managed by a processor of the environment absent intervention of a host of the environment. The functions include a resolve host page function; a pin function; and unpin functions.

Abstract: Input/output (I/O) communications subadapters, such as subchannels, of an I/O subsystem are dedicated to components, such as I/O devices, of the I/O subsystem. The subadapters provide information about the associated components, in response to the execution of I/O instructions. To enhance I/O connectivity, a plurality of sets of I/O subadapters is provided to an operating system image. This allows programs of the operating system image to access a same component via different sets of I/O communications subadapters. Further, it enables an operating system image to use more than 64k subchannels.