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Multi-Tasking File I/O in an Asynchronous/Synchronous Environment

IP.com Disclosure Number: IPCOM000100524D
Original Publication Date: 1990-May-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 50K

Publishing Venue

IBM

Related People

Gerstle, PJ: AUTHOR [+5]

Abstract

Disclosed is a means of utilizing an I/O device in an environment in which it is used by both asynchronous and synchronous operations.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 63% of the total text.

Multi-Tasking File I/O in an Asynchronous/Synchronous Environment

       Disclosed is a means of utilizing an I/O device in an
environment in which it is used by both asynchronous and synchronous
operations.

      In a system comprised of both synchronous and asynchronous
interrupt-driven operations, it is necessary to insure that the
synchronous operations have access to the system resources without
degrading the asynchronous operations unnecessarily.  In particular,
in a system where the critical resource is access to a hard disk, it
is essential that the synchronous operation be able to perform
read/write (R/W) operations when necessary without taking over the
resource entirely and locking out the asynchronous operation from
this resource.

      To facilitate this, two steps are taken:
      1.   The synchronous operation utilizes two data buffers to
minimize the number of read/write operations it performs.
      2.   The software intercepts all read/write operations to
determine their origin.

      Read/write operations originating with the synchronous
operation are performed normally.  In the case of all other
read/write operations, a check is first made to see if the
synchronous operation is active.  If it is not active, then the
read/write is performed normally.  If the synchronous operation is
active, then the read/write from the asynchronous operation will be
"partitioned" based on the synchronous data buffers.  A "dipstick"
i...