Early System Modeling
If the tasks can be represented as algorithms
expressed in a programming language, such as C,
the architect should consider early system modeling.
At this stage, tasks have not been allocated to
processors, and communications among tasks are
still expressed abstractly, either through message
passing or shared memory. This early modeling will
verify the functionality of the set of tasks and
it can measure the size, type and number of messages
or data operands transferred between tasks.
In theory, an early abstract system simulation
model can serve as the basis for sizing the computational
demands of each task. This information is not exact,
but it can yield important insights into both computational
and communications hot spots.
Using system simulation throughout the design
process has two advantages: 1) an early start to
simulation provides insight into bottlenecks, and
2) the model’s role as a performance predictor
gradually evolves into a role as a verification
test bench. To test a subsystem, a designer replaces
the subsystem’s high-level model with a lower-level
implementation model.
Tensilica’s Xtensa Modeling Protocol (XTMP)
Tensilica’s XTMP is an API and runtime environment
for rapid multi-processor description and analysis.
It provides a unified method to describe system
organization, communications mechanisms, and application
software, helping the design team quickly move
from back-of-the-envelope estimates to accurate
simulation. XTMP employs its own simulation engine
and generates SystemC-compatible models.
XTMP can be used for simulating homogeneous and
heterogeneous multiple processor subsystems as
well as complex uniprocessor architectures. The
XTMP API allows system designers to write customized,
multithreaded simulators to model complex systems.
Designers can instantiate multiple similar and
dissimilar Xtensa processor cores and use the XTMP
API to quickly connect these simulated processor
cores to memories, peripherals, interconnects,
and designer-defined subsystems.
More details about XTMP and a simple XTMP example
are shown in Chapter 4 of the book “Engineering
the Complex SOC: Fast, Flexible Design with Configurable
Processors,” by Chris Rowen, published
by Prentice Hall.
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