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Browse Prior Art Database

Virtual Start I O Fast Release

IP.com Disclosure Number: IPCOM000088417D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Brady, EF: AUTHOR [+3]

Abstract

Virtual start I/O (SIO) fast (SIOF) release extends the SIOF feature of the IBM System/37O to all processors of I/O requests (e.g., virtual machines and I/O processors) without modification to the requester (e.g., guest operating system).

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Virtual Start I O Fast Release

Virtual start I/O (SIO) fast (SIOF) release extends the SIOF feature of the IBM System/37O to all processors of I/O requests (e.g., virtual machines and I/O processors) without modification to the requester (e.g., guest operating system).

This is implemented by modifying the design of I/O request processors to permit presentation of status indicating start of an I/O operation when inboard verification (e.g., checking of virtual configuration) is completed, rather than when the actual status is presented by the system after all outboard checking (e.g., actual initial selection). This concept extends the S/370 architecture SIOF (which is supported only by multiple virtual storage and only on the Model 168) to all operating systems running on a processor of I/O requests.

SIOF per the S/370 architecture permits presentation of I/O initiated status when inboard checking is complete, rather than after all outboard checking is completed, as in SIO. Support of this feature as architected required modifications to the CPU and the operating systems. Virtual SIOF does not require any modifications to operating systems running on I/O processors which support virtual SIOF, and improves the performance of these systems.

For details on SIOF, refer to S/370 architecture.

As an example, VM (virtural machine) could be modified to support virtual SIOF, and guest operating systems (e.g., VS/1) would have their performance improved without modification...