Hewlett-packard Company

Randy J Matthews

Marvin D Nelson

Douglas L Voigt

Wade A Dolphin

It has been determined that considerable data which is written to stacks is of the type that does not require long term retention (i.e., it is only required to be valid for the duration of a procedure or function which created it). Accordingly, when a stack is employed to handle such data (and other similar data), invalidation and writes to main memory that ordinarily accompany accesses of such data (when the stack is held in a cache memory) can be avoided. The invention therefore improves memory performance by providing an overlay memory, to which is assigned a set of main memory addresses that are utilized for stack operations. When data is either read or written from/to the overlay memory, there is no further communication &ldquo;downstream&rdquo; to either a cache memory or main memory. In other words, the overlay memory is used for short term storage and accesses to the overlay memory are invisible to other memory elements of the system. There is thus no need to invalidate any data and nor to write such data to main memory. As a result, substantially improved memory operations result.

Integrated hierarchical memory overlay having invariant address space span that inactivates a same address space span in main memory

A multi-tasking, multi-initiator computing system includes an interfacing bus, at least one storage disk array connected to the interfacing bus, and multiple initiators connected to the interfacing bus to request I/O processes to be performed by the storage disk array. A disk array controller is provided in the storage disk array to assign the I/O requests received from the initiators to one of two types of job control data structures: (1) regular job control data structures that hold the information to process and complete the I/O request, and (2) minimized job control data structures that are temporarily used when no regular job control data structures are available. The disk array controller assigns the I/O request to the minimized job control data structures only in the event that no free regular job control data structures are available to hold the information from the I/O request. Each minimized job control data structure holds a subset of the information from the I/O request that is sufficient to reinitiate the I/O request for completion when a regular job control data structure once again becomes available. A method for operating a computing system and a memory data structure are also described.

System and method for handling I/O requests over an interface bus to a

In a disk storage system having dual controllers and mirrored memory therebetween, the mirrored memory is used to establish a robust communication path between the controllers to monitor and coordinate their activities. A reserved portion of the memory in each controller is designated as a messaging mailbox which is read and written by the owning controller but only read by the remote controller. The communication protocol between the controllers is tightly coupled to insure proper messaging. Furthermore, a sliding window interlock insures message detection and correctness. In addition, interrupt signals and timer based polling are used as a dual means for detecting communication requests and replies between the controllers.

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Boise, ID, United States of America

Randy J Matthews