Browse Prior Art Database

Firm Ordering Two-Level Partitioned Central Directory

IP.com Disclosure Number: IPCOM000105215D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Baldus, DF: AUTHOR [+2]

Abstract

Disclosed is a method of minimizing the size of a memory based directory by using a two-level directory structure.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 77% of the total text.

Firm Ordering Two-Level Partitioned Central Directory

      Disclosed is a method of minimizing the size of a memory based
directory by using a two-level directory structure.

      A method of minimizing the size of a memory based directory by
using a two-level directory structure.

      The first level of the directory consists of an n-way
associative directory where each entry contains multiple fields such
as the one shown below.

---------------------------------------------------
| State | Occupancy | Real address | Address Hash |
---------------------------------------------------

This invention focuses on the STATE field.

      The STATE field in the first level directory marks the entry as
empty, shared, exclusive, or busy.

      When a new request encounters a busy state in the first level
of the directory, it must then proceed to the second-level directory
to determine why it is busy.  The second level is a m-way fully
associative directory called the Pending Request Queue.  It contains
an entry for each BUSY first level directory entry.  Each Pending
Request Queue entry contains a STATE field capable of indicating more
than 64 states.  Other fields include information about the request
as well as first level directory information.

      When a new request encounters a non-busy first level directory
entry it will change the directory state to busy.  Then it will
create a new entry for the Pending Request Queue.  The state to be
ent...