Abstract: I/O measurement data for channels attached to logical control unit queues is obtained related to a plurality of logical control unit queues. A store secondary queue measurement data instruction specifies a range of queues for which extended secondary measurement blocks derived from the I/O measurement data are stored at a memory address specified by the store secondary queue measurement data instruction.

Abstract: An Extended Input/output (I/O) measurement word facility is provided. Provision is made for emulation of the Extended I/O measurement word facility. The facility provides for storing measurement data associated with a single I/O operation in an extended measurement word associated with an I/O response block. In a further aspect, the stored data may have a resolution of approximately one-half microsecond.

Abstract: An Extended Input/output (I/O) measurement block facility is emulated. The facility provides for the collection of relevant I/O measurement data, and the storing for later efficient retrieval of that data in an extended measurement block. The stored data relates to the performance of an I/O subchannel.

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: I/O measurement data associated with the performance of an I/O operation process is gathered during the I/O process. The I/O measurement data is saved in an IRB memory location specified by a test subchannel instruction. An I/O interrupt signals the completion of the I/O operation process.

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: Disclosed are a method and system for parallel execution of recovery in a non-homogeneous multi-processor environment. The method defines criteria how to decide which recovery actions are to be performed, and on which processor. If multiple recovery actions are pending, the goal is to execute them in parallel on multiple processors. This is much more efficient than the traditional approach of one processor doing all the required recovery. In addition, in large, non-homogeneous systems such a single processor capable of doing the complete recovery might not be existing at all due to technical limitations. The method of this invention also defines rules and mechanisms how multiple processors executing recovery in parallel can access shared resources while avoiding deadlock situations. This includes accessing resources that are currently owned by another processor.

Abstract: A bi-directional and full duplex facility for permitting both the IO processor and the Channel to write CCA messages on their respective queues at the same time. IOP messages to the channel are stored on the TO_CHN queue and Channel messages to the IOP on the TO_IOP queue. CCA Queues replace hardware CCAs due to increasing transmission capabilities of current IO processors and Channel processors. Even though the mechanism is similar, the present invention provides some benefits in the use of signaling. The IOP does not have to signal the Channel each time it puts something on its outbound queue. Each queue contains multiple slots. This allows the IOP and Channel to write multiple messages on the targeted queue without encountering a CCA busy signal. The actual queues are now structured in hardware system memory.

Abstract: An Input/output (I/O) measurement block facility is provided that creates subchannel measurement blocks (comprising device busy values) related to performance of an I/O operation of a subchannel, wherein a device busy time value is a sum of time intervals when the subchannel is device busy during an attempt to initiate any one of a start function or a resume function at the subchannel.

Abstract: I/O measurement data for channels attached to logical control unit queues is obtained related to a plurality of logical control unit queues. A store secondary queue measurement data instruction specifies a range of queues for which extended secondary measurement blocks derived from the I/O measurement data are stored at a memory address specified by the store secondary queue measurement data instruction.

Abstract: I/O measurement data associated with the performance of an I/O operation process is gathered during the I/O process. The I/O measurement data is saved in an IRB memory location specified by a test subchannel instruction. An I/O interrupt signals the completion of the I/O operation process.

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.