Browse Prior Art Database

Partial Access Lookaside Buffer Purges

IP.com Disclosure Number: IPCOM000120764D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 45K

Publishing Venue

IBM

Related People

Frey, BG: AUTHOR

Abstract

Disclosed is a group of instructions which will decrease the performance penalty associated with maintaining consistency between the access tables in main storage and the Access Lookaside Buffer (ALB) in the ESA/370* architecture. To realize performance benefits, they must be used in conjunction with an ALB which contains Access List Origins (ALOs) and/or Access List Entry Tokens (ALETs). More economical ALB implementations can assure compatibility by performing PALB (Partial Access Lookaside Buffer) for every partial purge operation.

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Partial Access Lookaside Buffer Purges

      Disclosed is a group of instructions which will decrease
the performance penalty associated with maintaining consistency
between the access tables in main storage and the Access Lookaside
Buffer (ALB) in the ESA/370* architecture.  To realize performance
benefits, they must be used in conjunction with an ALB which contains
Access List Origins (ALOs) and/or Access List Entry Tokens (ALETs).
More economical ALB implementations can assure compatibility by
performing PALB (Partial Access Lookaside Buffer) for every partial
purge operation.

      Two new instructions are specified, each with two variations.
Given the large number of fields defined to be part of the access
register translation process, many other partial purges are possible.
These two seem to be among the most desirable for maintaining
consistency from an operating system's point of view.

      The first instruction purges all entries in the ALB that are
related to a particular ALO.  The ALO is specified in a general-
purpose register.  Execution involves a search of all ALB entries,
and subsequent invalidation of at least those entries which were
created using the access list defined by the ALO.

      The second instruction purges all entries in the ALB that are
related to a particular ALET.  The ALET is specified in a general-
purpose register.  Execution involves a search of all ALB entries,
and subsequent invalidation of at least those entri...