Multiprocessor research at

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1 Δεκ 2013 (πριν από 3 χρόνια και 7 μήνες)

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Multiprocessor research at
Åbo Akademi

Ralph
-
Johan Back

Early 80’s


Work on distributed systems


joint work with Reino Kurki
-
Suonio


formalizing, constructing, analyzing, verifying
distributed systems


point
-
to
-
point networks, wlans, etc


courses on distributed systems at ÅA


research on language CSP (C.A.R. Hoare)


very theoretical work, needed some practical
case studies to look at

Mid 80’s


Inmos starts designing the
transputer



Special processor that has four links for
communication with neighbours


Specially designed for building parallel
processors

T800

Hathi
-
project


VTT Oulu contacted us, wanted to build a
parallel computer


Tapani Äijänen, Kari Leppänen from VTT


TEKES project (Hathi, 1986
-
88):


VTT built hardware


ÅA built software


First version: Hathi
-
1, 16 processors


Mats Aspnäs project manager from ÅA


Used for experimentation


Lots of case studies in building parallel systems

Finsoft III program


TEKES starts a new large research program
(Finsoft, in three parts, 1988
-
91)


I was director of Finsoft III
-

parallel processing and
neural networks


12 different research projects in Finsoft III, 7 in
parallel processing and 5 in neural networks


ÅA had 2 large projects: Millipede and Centipede


Millipede: Massively parallel processors


Centipede: Construction and correctness of Parallel Systems


Quite a large number of people enganged in Millipede


U. Solin, Hong Shen got Ph.D. from this


many M.Sc. thesis.


Millipede


Built Hathi
-
2 in Millipede


VTT/Oulu built hardware


ÅA built software


Largest supercomputer in Finland at that time


Connected to the university network (internet)


A reasonable number of research groups were using
Hathi
-
2, in different universities


Different kinds of applications, mainly CS and
scientific computing


Many Ph.D. and M.Sc thesis around Hathi
-
1 and
Hahi
-
2.


Hathi
-
2



Hathi
-
2 construction


100 Transputer 800 floating point processors


Connected in a mesh structure


Dynamically reconfigurable connection structure


25 smaller Transputers connected in a ring, to
monitor and control the floating point processors


Physically


size of a larger refrigator,


with 25 boards,


each board containing 4 T800 and 1 smaller
transputer


Hathi
-
2


Hathi
-
2 system software


Reconfiguring the conection structure


Mapping logical processor structure onto physical
structure


Monitoring software for performance measurements


Hathi
-
2 application software


Nuclear physics


Solving differential equations


CFD (Computational fluid dynamics)


Cosmology


Full text retrieval


....


Main challenges


Writing software as collection of parallel processes was
difficult


Occam language from Inmos based on CSP


orchestrating communication by means of message passing


problems with deadlocks and livelocks


Lots of algorithmic problems


laying out a logical process net on a physical processor network
required strong heuristics


Monitoring computation without interfering required careful
embedded system design


Partitioning software to allow for parallel computation


In the end, writing software for massively parallel
processors was not that much more difficult that writing
ordinary software

Early 90’


I went for a sabbatical to Caltech (1991
-
92)


Center for massively parallel computer research


Chuck Seiz built first cosmic cube


Chuck was working on really large processor array
(16K processors)


However


I worked mostly on formal methods in programming


And participated in Alain Martins group on the design
of asynchronous VLSI circuits


Was not that intrested in multiprocessor hardware
design

T9000 transputer


We planned to build Hathi
-
3


T800 processors had become too slow compared to the
competitors


We needed the new T9000 transputers


very efficient


had wormhole routing, so arbitrary dynamic routing at run time


competed with best Intel and Motorola processors at that time


Inmos had difficulties in building T9000 in quantity


quality of produced processors was not good enough


Inmos was bought up by other companies


in the end, they stopped the development of a new transputer
generation

End of Hathi


Did not want to continue working with
other processors



Intel or Motorola processors were much
inferior to Inmos transputers for parallel
systems


Could not build own transputer


Hathi
-
3 was never built


Hathi
-
2 was deplugged in 93
-
94.