Browse Prior Art Database

Multisequencing a Single Instruction Stream Meta High-End Machine Dealer Role of Branch Prediction Mechanism In Segment Swtiching

IP.com Disclosure Number: IPCOM000104483D
Original Publication Date: 1993-Apr-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 171K

Publishing Venue

IBM

Related People

Ekanadham, K: AUTHOR [+3]

Abstract

Multisequencing a Single Instruction Stream (MSIS) is a uniprocessor organization in which a set of processing elements (PE) working in concert execute Segments of the instruction stream. The Segments are either P-Segments, normal uniprocessor instruction stream portions, that are processed in the E-MODE of MSIS and produce Z-Segments, or the Z-Segments that are processed in Z-MODE by MSIS. The main difference between E-MODE and Z-MODE is that during E-MODE each PE sees all instructions in the Segment and executes the ones that are assigned to it, but during Z-MODE, a PE only sees the instructions assigned to it.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 35% of the total text.

Multisequencing a Single Instruction Stream Meta High-End Machine Dealer Role of Branch Prediction Mechanism In Segment Swtiching

      Multisequencing a Single Instruction Stream (MSIS) is a
uniprocessor organization in which a set of processing elements (PE)
working in concert execute Segments of the instruction stream.  The
Segments are either P-Segments, normal uniprocessor instruction
stream portions, that are processed in the E-MODE of MSIS and produce
Z-Segments, or the Z-Segments that are processed in Z-MODE by MSIS.
The main difference between E-MODE and Z-MODE is that during E-MODE
each PE sees all instructions in the Segment and executes the ones
that are assigned to it, but during Z-MODE, a PE only sees the
instructions assigned to it.

      As a PE sees all instructions in E-MODE, each PE can create the
Z-CODE it will require to re-execute the  Segment as a Z-Segment, the
Z-CODE being stored in the Z-CACHE, and associated with instructions
in the Z-CODE are S-LISTS and D-LISTS as appropriate.  An S-LIST
instructs the PE, in the Z-MODE, that one or more of the source
registers in an instruction assigned to it is set by another
instruction that is executed on another PE, an S-LIST is a receiving
obligation.  The D-LIST instructs the PE in the Z-MODE as to the
names of PEs that require the values of the register(s) that are
being set by an instruction that is assigned to it.  A D-LIST entry
is a sending obligation.

      The set of instructions assigned to a single PE can be further
delineated as THREADS.  A THREAD is a sequence of instructions in the
original conceptual order and a Thread is associated with a register
file which is either real or virtual.  There are no sending or
receiving obligations between instructions within a THREAD and the
THREAD is the smallest unit of aggregation of instructions from a
SEGMENT.

      MSIS HEM is a High-End Machine design that uses multiple
decoders within a single processor in the place of separate processor
elements (PEs).  A single  Instruction  Processing Unit (IPU)
executes all instructions in MSIS HEM albeit through a multiplicity
of register files that are associated with the THREADS.   MSIS META
HEM is a Multiple Execution Thread Architecture that separates the
THREADS from the next higher aggregate of instructions the DECODER.
Thus the action of S-LIST and/or D-LIST entries  within  the Z-CODE
activates and deactivates the THREADS and alternate THREADS are
decoded.  Individual instructions while executing carry an indication
as to which SEGMENT, DECODER, and THREAD to which they belong.  The
information concerning the DECODER and THREAD is derived from the
Z-CODE itself.  The SEGMENT index is assigned sequentially at  each
SEGMENT SWITCH.  Segment  switches occur at points in the code where
the Z-SEGMENT terminates or where a Branch Wrong  Guess  has been
detected.

      The conceptual ease with which a Z-SEGMENT can be re-entered,
and...