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Multisequencing a Single Instruction Stream Meta High-End Machine Path, Segment, Decoder, Thread - The Motif of Organization

IP.com Disclosure Number: IPCOM000104327D
Original Publication Date: 1993-Apr-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 158K

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.

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Multisequencing a Single Instruction Stream Meta High-End Machine Path, Segment, Decoder, Thread - The Motif of Organization

      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
instruction 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.

      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.  Individual  instructions while executing carry an
indication as to which SEGMENT,  DECODER,  and  THREAD  to  which
they belong.

      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  registers  files  that  are associated with the
THREADS.  MSIS META HE...