LLFRP: An Energy Efficient Variant of LLF with Reduced Pre-emptions for Real – Time Systems

Abstract

Energy efficiency without performance degradation
is a challenge in battery operated real-time systems. One way to
achieve this is by optimizing scheduling parameters like
preemptions and cache activities. In this work, we present an
energy efficient variant of Least Laxity First scheduler – Least
Laxity First with Reduced Preemptions – that reduces the
number of preemptions in a schedule. We prove that our
scheduler offers the same feasibility as LLF. We present
extensive analysis through experimental results to show that our
variant significantly reduces the number of preemptions. Our
results also show that the number of preemptions in the schedule
output by this algorithm is close to the minimum possible
number. Our analysis addresses the following metrics:
preemptions, cache impacts, decision points, response time,
response time jitter, latency, time complexity and energy
consumption. In this work the proposed algorithm is compared
with dynamic priority scheduling algorithms like RM, EDF, nonstrict
LLF and strict-LLF. The result shows that the proposed
algorithm offers 4.25% of energy saving in comparison with
EDF, RM and non-strict LLF and it offers 7% energy saving in
comparison with strict-LLF. The result also shows that the
proposed algorithm increases the scheduling utilization by 4% in
comparison with EDF, RM and non-strict LLF and it increases
scheduling utilization by 6% in comparison with strict-LLF.