Browse Prior Art Database

MSIS Finding a Better Schedule for 32 PEs

IP.com Disclosure Number: IPCOM000103699D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 106K

Publishing Venue

IBM

Related People

Ekanadham, K: AUTHOR [+6]

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 52% of the total text.

MSIS Finding a Better Schedule for 32 PEs

       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 PE's 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.

      An MSIS schedule for n PEs is limited by two factors:
o    the number of PEs
o    the speed-up associated with infinite number of PEs, the
so-called Maximum Dependency Time (MDT).

      In schedules generated for small Z-SEGMENTS the performance for
each level of n, where n is the number of PEs, follows one or the
other limitation.  For longer Z-SEGMENTS which can be represented as
repetitions of instructions within a Z-SEGMENT that undergo different
assignments, the performance at 32 PEs stands out as not being
limited by either limitation.  The approach outlined below can
improve the performance of 32 PEs by a process called blocking.

      The constraints on assignment are:
o  The time-slot associated with the assignment of an instruction, to
a PE must exceed the MIN_SLOT of the instruction (the MIN_ SLOT being
defined as the earliest decode time slot that is later than the time
of the availability of all input to the instruction.) Each timing of
availability is based on the timing of the instruction that sets...