Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

MSIS Determining the Number of Virtual PE-ID

IP.com Disclosure Number: IPCOM000103670D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 4 page(s) / 170K

Publishing Venue

IBM

Related People

Ekanadham, K: AUTHOR [+4]

Abstract

MSIS (Multisequencing a Single Instruction Stream) is a uniprocessor organization in which a set of processing elements (PEs) 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 40% of the total text.

MSIS Determining the Number of Virtual PE-ID

       MSIS (Multisequencing a Single Instruction Stream) is a
uniprocessor organization in which a set of processing elements (PEs)
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 all PEs see 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.

      Up to this point the distinction between THREADS and PE did not
exist as the instructions within a given Z-SEGMENT that would be
executed by a single PE were constrained to be in conceptual
sequence, i.e., they formed a single THREAD.  The ability to used
virtualized names for a given PE, what shall be called PE-ID or
THREADS, can be used to fill in the decode cycles that are skipped by
the constraint that is associated with all instructions on a PE being
in conceptual sequence.  This allows shorter schedule lengths
(makespans) to be developed and creates the opportunity to minimize
the number of such names.  That is, given the set of all instructions
that have been scheduled to decode cycles on a given PE, what is the
smallest number of THREADS, or virtualized PE-ID that can be formed
if the instructions within a PE-ID must be in conceptual sequence.
An algorithm is proposed to accomplish this.  The Z-CODE in the
sequence of DECODE SLOTS is not in conceptual sequence and is called
OOS (Out Of Sequence) Z-CODE.  It must be segregated into PE-IDs
within PE to form in sequence instructions that can be executed
properly in Z-MODE.  The concept of OOS Z-CODE withi...