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Mini-Ops - a Microcoded Data Transfer Scheduling and Execution System for the Optimized Control of an I/O Controller Cache Memory

IP.com Disclosure Number: IPCOM000043154D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Dixon, JD: AUTHOR [+3]

Abstract

Using a disk file input/output (I/O) controller to schedule and execute data transfer and control operations in an optimized manner through a controller cache memory in the controller is described. With proper control of the cache memory, all actions necessary to complete a given command can be broken down into smaller operations called mini-ops. The mini-ops are saved in a dedicated area of the controller random-access memory (RAM) for use by the mini-op execution routine. The mini-op format is free-form so that new operations can be defined at any time, and as much information as is necessary to perform the operation may be included in the mini-ops.

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Mini-Ops - a Microcoded Data Transfer Scheduling and Execution System for the Optimized Control of an I/O Controller Cache Memory

Using a disk file input/output (I/O) controller to schedule and execute data transfer and control operations in an optimized manner through a controller cache memory in the controller is described. With proper control of the cache memory, all actions necessary to complete a given command can be broken down into smaller operations called mini-ops. The mini-ops are saved in a dedicated area of the controller random-access memory (RAM) for use by the mini-op execution routine. The mini-op format is free-form so that new operations can be defined at any time, and as much information as is necessary to perform the operation may be included in the mini-ops. As an example of mini- op scheduling, the first step necessary to execute a read data command is to determine if the data requested by the central processing unit (CPU) is resident in the controller cache. The amount of data requested determines the number of mini-ops necessary to control the command's execution. Scheduling is performed by the mini-ops scheduling routine. The mini-op contains the necessary information as to where data is to be placed and/or retrieved from cache, how much data is to be transferred, and where the requested data will reside in the CPU main storage. If all the requested data is resident in cache, the disk file is not accessed and execution of the mini-ops necessary to transmit the requested data from cache to the system begins immediately after scheduling is complete and is known as a "cache hit". When all the requested data is not in cache, a read operation is issued to the disk file to obtain the data needed to satisfy the using system's request. The mini-ops necessary to control the data transfer in and out of cache are then scheduled. This is known as a "cache miss". Similar mini-op sequences are generated for write data commands. The mini-op data ...