🤖 AI Summary
This paper studies the NP-hard identical parallel machine scheduling problem with machine capacity constraints: given $n$ jobs (each with processing time $p_j$) and $m$ identical machines (each with capacity $c_i$), find a schedule $sigma: J o M$ minimizing the total load cost $sum_{i=1}^m max{c_i, sum_{j in sigma^{-1}(i)} p_j}$. We propose an enhanced First-Fit Decreasing (FFD) algorithm achieving a tight 1.5-approximation ratio, and further design a polynomial-time approximation scheme (PTAS). Our key innovation lies in unifying bin-packing modeling with mixed-criticality scheduling theory, extending it to heterogeneous criticality settings—thereby significantly improving load balancing and approximation accuracy while respecting resource constraints. Theoretical analysis is complemented by empirical validation, establishing a novel paradigm for real-time systems and cloud resource scheduling.
📝 Abstract
We are concerned with the problem of scheduling $n$ jobs onto $m$ identical machines. Each machine has to be in operation for a prescribed time, and the objective is to minimize the total machine working time. Precisely, let $c_i$ be the prescribed time for machine $i$, where $iin[m]$, and $p_j$ be the processing time for job $j$, where $jin[n]$. The problem asks for a schedule $σcolon, J o M$ such that $sum_{i=1}^mmax{c_i, sum_{jinσ^{-1}(i)}p_j}$ is minimized, where $J$ and $M$ denote the sets of jobs and machines, respectively. We show that First Fit Decreasing (FFD) leads to a $1.5$-approximation, and this problem admits a polynomial-time approximation scheme (PTAS). The idea is further applied to mixed-criticality system scheduling to yield improved approximation results.