Browse Prior Art Database

High Priority Lock Enqueue

IP.com Disclosure Number: IPCOM000106814D
Original Publication Date: 1993-Dec-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Lee, W: AUTHOR [+3]

Abstract

VM/ESA* provides an asynchronous Error Recovery Procedure (ERP) environment for preferred guests, to minimize the time spent in instruction simulation. The High Priority Lock is the key serialization component for this environment.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

High Priority Lock Enqueue

      VM/ESA* provides an asynchronous Error Recovery Procedure (ERP)
environment for preferred guests, to minimize the time spent in
instruction simulation.  The High Priority Lock is the key
serialization component for this environment.

      Devices continue to grow both in function and complexity.  In
turn, the maintenance and support facilities (ERPs) that are
developed to support them, have also similarly evolved.  These
procedures can consume a significant amount of time to complete their
required tasks.  The existing methodology of holding a preferred
guest in instruction simulation, while these large time consuming
procedures process, cause an unacceptable degradation in guest I/O
performance.  This synchronous environment was dictated by the device
lock which had to be held for the ERPs, so that device recovery would
be properly synchronized and the I/O schedule ordering preserved.

      In this new asynchronous environment, the ERPs instead of
executing synchronously, would be stacked on the device lock and
executed sometime later after the preferred guest process dropped the
device lock.  Because the device lock is a deferred lock, there
exists a potential exposure that additional requests for the device
lock could preclude the ERPs from acquiring the lock for an extended
period.  If other tasks were to acquire the lock prior to the ERPs,
major serialization problems would be eminent.

      To address this problem, a high priority locking metho...