Non-Intrusive Runtime Monitoring for Manycore Prototypes

Rapid prototyping is widely used, essential technique for developing
novel computing architectures. While simulation-based approaches
allow to examine the design under test, the observability of FPGAbased prototypes is limited as they can behave like a black box.
However, for verification and design space exploration purposes
it is crucial to obtain detailed information on the internal state of
such a prototype. In this work we propose an architecture to gather
detailed internal measurements during execution and extract them
from the design under test without impacting its runtime behavior.
It is specifically designed for low resource usage and minimal impact on timing, leaving more resources for the actual prototyped
system. Our proposed architecture offers several different interface
modules for various signal sources, including register capturing,
event counters and bus snooping. We present an estimate of achievable bandwidth and maximum sample rate as well as a demanding
case-study with a tiled manycore platform on a multi-FPGA prototyping platform. Experimental results show up to 32 million 4-byte
measurements per second, saturating a gigabit Ethernet connection.
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The monitoring system has proven to be very useful when working
with an FPGA-based manycore prototype, as it is an essential tool
to reveal incorrect behavior and bottlenecks in hardware, operating
system and applications at an early stage.