The MULTICUBE Design Flow - Multi-objective Design Space Exploration of Multiprocessor SoC Architectures - page 15

￿ Simulation time: the simulation of the executable model with a single configura-

tion of parameters is carried out (this phase is similar to the one that is performed
with the manual approach);

￿ Automatic DSE overhead: this step includes the automatic assessment of the

results, the automatic selection of the next configuration to be simulated (model
selection) and the data transfer operations between the simulator and the design
space exploration tool and its corresponding storage into the design database.

Figure 1.6 describes the automatic exploration procedure. The exploration of the
design space is done by numerical/objective criteria. The Design Space Exploration
tool (or “exploration engine”) will change systematically all the parameters for each
analysis and will evaluate the best result by adopting numerical formulas. The setup
phase can be considerably longer than the set up of a manual exploration, since it
usually requires an extended definition of the model to interact with the exploration
engine, the definition of the proper optimization strategy and the definition of the
multi-objective goals to be achieved. However, after that, the model evaluations
(Simulation Time) is similar to the simulation time required in the manual approach,
except for a further step (Automatic DSE overhead) that involves the automatic
assessment of the results, the automatic selection of the next configuration to be
simulated (model selection) and the time spent for data communication and storage.
Based on the past experience of ESTECO to deal with industrial customers, even
if a single evaluation takes just a few seconds, it is difficult that a designer using
a manual optimization procedure can evaluate more than seven designs of medium
complexity within one hour. The designer has to go through all steps described
before, editing the configuration parameters, running the analysis, reading and ana-
lyzing the results, etc. In this case, it is expected that in one person-day (10 h), the
designer can run at most 70 designs. For the same problem, experience shows that an
automatic approach can handle something like 600 designs per hour, which means
about 14,400 designs per day. Since the automatic procedure can work 24 four hours
a day, including weekends and holidays, the advantages of the automatic procedure
are very clear.
However, there are other advantages of the automatic exploration procedure. In the
automatic exploration, all data concerning previous evaluations are always stored in a

Simulation Time

Model Setup

Automatic DSE Overhead

Fig. 1.6 Automatic exploration procedure