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Metaparallelism - Pathing and Directed Acylic Graphing in Speculative Executions

IP.com Disclosure Number: IPCOM000106017D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 6 page(s) / 238K

Publishing Venue

IBM

Related People

Ekanadham, K: AUTHOR [+2]

Abstract

Metaparallelism is a process that determines the form of parallelism that is to be used in a specific application. Metaparallelism has two interfaces:

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 21% of the total text.

Metaparallelism - Pathing and Directed Acylic Graphing in Speculative Executions

      Metaparallelism is a process that determines the form of
parallelism that is to be used in a specific application.
Metaparallelism has two interfaces:

o   Information derived from prior executions.

o   Explicit statements made in the program or compiler output that
    bear on the form of parallelism.

Metaparallelism uses aspects of program behavior as it relates to the
capabilities of the Metaparallel Processor to cope with this behavior
to determine the type of parallelism that is to be pursued.
Metaparallelism employes speculation, that is, allocation of
resources to computations without a guarantee that these computations
are required, in order to complete the application in the faster
time.

The choice of parallelisms that metaparallelism can select from are:

o   Path oriented forms of parallelism.

o   Path oriented forms of parallelism with speculation.

o   Computation oriented parallelism with bifurcation at branches.

o   A set of independent paths that intercommunicate by sending
    messages to each other.

o   A combination of the above.

Metaparallelism employs means at its disposal to alter the form of
parallelism specified by the programmer/compiler at the source level
and to notify the programmer about significant aspects that interfere
with the parallelization of the application.

      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 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...