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Browse Prior Art Database

Inter-Processor 802 Interface

IP.com Disclosure Number: IPCOM000112460D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27

Publishing Venue

IBM

Related People

Dobbelstein, SL: AUTHOR [+2]

Abstract

The Dual Processor Server makes use of an additional CPU installed in the machine to increase performance. The additional CPU is provided on an adapter card installed in the machine. Several pieces of the Server are off-loaded to the adapter card processor, namely the File System, the Ring 0 File Server and the Protocol Stack. This is diagrammed in Fig. 1. Off-loading these pieces improves performance in two ways. First, loading these pieces on the adapter card processor allows them to run in parallel with the remainder of the operating system that is loaded on the planar processor. This means that disk requests or network activity can be handled at the same time as applications that are running on the planar processor.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 18% of the total text.

Inter-Processor 802 Interface

      The Dual Processor Server makes use of an additional CPU
installed in the machine to increase performance.  The additional CPU
is provided on an adapter card installed in the machine.  Several
pieces of the Server are off-loaded to the adapter card processor,
namely the File System, the Ring 0 File Server and the Protocol
Stack.  This is diagrammed in Fig. 1.  Off-loading these pieces
improves performance in two ways.  First, loading these pieces on the
adapter card processor allows them to run in parallel with the
remainder of the operating system that is loaded on the planar
processor.  This means that disk requests or network activity can be
handled at the same time as applications that are running on the
planar processor.  Second, off-loading these components frees up CPU
cycles on the planar so that it can do other work, such as run a data
base.

      The data base server can use NetBIOS* or APPN* to communicate
with its clients.  APPN uses the 802.2 protocol.  For various
technical reasons it is best to move the entire protocol stack over
to the adapter card processor.  This includes 802.2.  The problem
then arises as to how to have the data base server, which is loaded
on the planar processor, communicate with the 802.2 driver (LANDD)
which is loaded on the adapter card processor.  What is needed is an
interface that will allow applications on the planar processor that
use the 802.2 protocol to communicate with LANDD which is running on
the adapter card processor.

      OVERVIEW - There are two device drivers required to enable the
redistribution of the 802.2 protocol.  The first part is the 802
Shell, which runs on the planar processor.  Its function is to
intercept the 802.2 requests and reroute them to the adapter card
processor.  The 802 Server on the adapter card processor will receive
the requests and call LANDD.  Upon completion of the request, the 802
Server will return the completed request to the 802 Shell.  The 802
Shell will then pass the completed request back to the application
that made the request.

      The main task of the device drivers is to translate addresses
so that they are valid for the processor on which they are running.
Any pointers in an 802.2 request from the application running on the
planar processor must be translated to addresses that are valid for
LANDD which is running on the adapter card processor.  Any pointers
that are returned from LANDD on the adapter card processor must be
translated to addresses that are valid for the application running on
the planar processor.

      Fig. 2 shows a diagram of the flows between the application
that talks 802, the 802 Shell, the 802 Server, and LANDD.  Notice
that the CCBs issued by the application to the 802 Shell and the CCB
completions, data receives and events returned by the 802 Shell are
paralleled in the interface between the 802 Server and LANDD.  The
new stuff that needs d...