Browse Prior Art Database

Inter Machine Request Interface for System Services

IP.com Disclosure Number: IPCOM000088415D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 4 page(s) / 38K

Publishing Venue

IBM

Related People

Davidson, GA: AUTHOR [+2]

Abstract

System Services invoked from a Problem Program effectively "suspend" the requesting application by transferring instruction execution to the called service routine. This serial mode of operation is the natural extension of the traditional system hardware capability (i.e., SINGLE CPU). However, the cost of an instruction executor relative to total system cost continues to decrease. Therefore, the design of future system service interfaces and user applications should be developed to obtain maximum parallelism between the user application program and the requested system service program. Presently, traditional operation systems offer a type of parallelism in those areas where the requested service involves a delay in time and is identified with a Hardware Capability. The two most common examples are:. .

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Inter Machine Request Interface for System Services

System Services invoked from a Problem Program effectively "suspend" the requesting application by transferring instruction execution to the called service routine. This serial mode of operation is the natural extension of the traditional system hardware capability (i.e., SINGLE CPU). However, the cost of an instruction executor relative to total system cost continues to decrease. Therefore, the design of future system service interfaces and user applications should be developed to obtain maximum parallelism between the user application program and the requested system service program. Presently, traditional operation systems offer a type of parallelism in those areas where the requested service involves a delay in time and is identified with a Hardware Capability. The two most common examples are:. . Data Transfer concurrent with instruction execution . Time increment/decrement concurrent with instruction execution.

Note that little CPU parallelism exists between the requesting user code string and system logic execution. This is due both to the nature of the service interface and the hardware/software design which offers a generalized function capability to each processor rather than dedicating processors to specific functions.

As Instruction Processing Units (IPU) become less expensive (as indicated by the microprocessor trend), systems can well afford dedicated processor functions that will ultimately affect the design of: . System Hardware . System Software . User Applications

The advantages to be gained from such parallel systems include: . Performance improvement by executing both problem program and system logic concurrently. . Removal of implicit "Suspend" conditions of the requesting user program. . Asynchronous notification denoting completion of a requested service, thereby giving flexibility to the invoking program as to whether an uncompleted service warrants an explicit suspend. . Flexibility in the design of a service processor (and software) to treat all interrupt requests as asynchronous and separately maskable. . Inherent reliability afforded by isolating function to specific processors, thereby aiding:. .. Firm interface definition which cannot be circumvented by: ... Branching into a System Control Program (SCP) Service Routine -- since the requested service may be physically remote.

An example of a current serial system interface so transformed may be PROGRAM LOAD .. followed at some later point in time with a WAIT which checks for the satisfactory completion of the service request. Thus, just as data transfer and instruction execution occur simultaneously today, user program execution occurs in parallel with system service logic.

A Parallel Processor Prototype developed to execute a DOS/VS release creates a potential parallel service request from every user program invocation of a Supervisor Call Instruction (SVC) or Program Check (PC) interrupt. However, o...