Performance Evaluation of Highly Concurrent
Computers by Deterministic Simulation

Simulation is presented as a practical technique
for performance evaluation of alternative 
configurations of highly concurrent computers.  A technique
is described for constructing a detailed 
deterministic simulation model of a system.  In the model
a control stream replaces the instruction and 
data streams of the real system.  Simulation of the
system model yields the timing and resource usage 
statistics needed for performance evaluation, without
the necessity of emulating the system.  As a case 
study, the implementation of a simulator of a model
of the CPU-memory subsystem of the IBM 360/91 is 
described.  The results of evaluating some alternative
system designs are discussed.  The experiments 
reveal that, for the case study, the major bottlenecks
in the system are the memory unit and the fixed 
point unit.  Further, it appears that many of the sophisticated
pipelining and buffering technique simplemented 
in the architecture of the IBM 360/91 are of little
value when high-speed (cache) memory is used, as 
in the IBM 360/195.

CACM November, 1978

Kumar, B.
Davidson, E.

Performance evaluation, deterministic simulation,
control stream, concurrent computers

6.20 8.1

CA781103 DH January 26, 1979  11:26 AM

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