Browse Prior Art Database

Cache-Oriented Local Memory Control Mechanism for Distributed Shared Memory

IP.com Disclosure Number: IPCOM000112535D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 92K

Publishing Venue

IBM

Related People

Fukuda, M: AUTHOR [+3]

Abstract

Disclosed is a mechanism which assures to map entire Distributed Shared Memory (DSM) space onto local memories and keeps the certain space for caching remote data in each local memory.

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

Cache-Oriented Local Memory Control Mechanism for Distributed Shared
Memory

      Disclosed is a mechanism which assures to map entire
Distributed Shared Memory (DSM) space onto local memories and keeps
the certain space for caching remote data in each local memory.

      This mechanism defines a shared ratio for each node's local
memory.  The shared ratio is the upper limit on the ratio of the
shared data included by the corresponding node's local memory.  Under
the defined values of shared ratio for each node's local memory, the
mechanism calculates a maximum size of total DSM space.  Then the
mechanism manages the shared data allocation automatically to keep
the shared ratio.  In other words, the mechanism keeps the space for
the data once loaded into the system.

      First, the a generalized structure of the distributed shared
memory system that uses the local memory as the cache of the
distributed shared memory space, in other words, Cache Only Memory
Architecture (COMA), is briefly described.  Second, the disclosed
mechanism is fully described.

      COMA is constructed with computers connected by high-speed
communication media.  Each node has more than one processor.  Each
processor connected to the local bus via the bus interface,  and 1 or
more level cache.  Several I/O systems are connected to the local bus
or I/O bus.

      Each node also has a tag memory corresponding to the local
memory,  a memory controller controlled by the tag memory, and a
communication controller.  The memory controller steals the processor
access to the local memory, and checks whether data is in the local
memory, by referring to the tag memory.  When the data is in the
local memory, it is returned to the processor from the local memory.
When the data is in the remote node, the data request message is sent
via the communication controller.  The data supplied from the remote
node is returned to the processor.

      The mechanism controls the data mapping...