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MSIS Conditional Branch and Equalize

IP.com Disclosure Number: IPCOM000103649D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 103K

Publishing Venue

IBM

Related People

Ekanadham, K: AUTHOR [+4]

Abstract

MSIS (Multisequencing a Single Instruction Stream) is auniprocessor 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 52% of the total text.

MSIS Conditional Branch and Equalize

       MSIS (Multisequencing a Single Instruction Stream) is
auniprocessor 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.

      Within MSIS no provision has been made for instructions that
operate within the Z-MODE that were not part of the original
execution sequence.  This oversight can be corrected if it can be
determined that the operations within the Z-MODE of the processor can
gain an advantage from such additional instructions.  One example of
such an instruction is a branch operation that can be placed on a
contour within the Z-CODE so that all PEs will encounter the branch
at the same logical point in the execution sequence, i.e., between
two successive instructions in the original execution sequence.

      The branch instruction so placed is not a branch within the
original code but a branch in the Z-MODE to a set of locations, a
contour, within the Z-CODE, and can be conditional and PRIMED prior
to the dispatch of the Z-SEGMENT so that the Z-SEGMENT will take it
or ignore it. ...