Improving the LEON Spacecraft Computer Processor for Real-Time Performance Analysis

摘要

This paper presents an enhanced version of theLEONarchitecturewith a performance-monitoring unit, includingnperformance counters for different events and a trace buffer. Through this enhancement the user or systemengineernis able to obtain information about the cache behavior and the execution path of a whole program or a fragment ofncode. This development introduces several advantages over simulators, such as allowing tests to be performedndirectly on the real target in a nonintrusive mode. Taking advantage of this enhancement, a suite of tests for cachencharacterization and evaluation has been developed. The results of this study can contribute to modeling thenbehavior of the LEON architecture in areas such as worst-case execution-time estimation and probabilistic analysis.nThe newfeatures can be very useful during the validation and verification phase of the real-time software, supportingncode coverage techniques and reducing the execution-time variability due to hardware effects such as cache andnpipelines.The field-programmable gate-array resources employed by the performance-monitoring unit developed innthis paper are low, on the order of 3–5%, with the exception of an increase of 37%in the use of embedded memorynblocks.