As datacenters continue to grow in scale, their energy consumption and resulting carbon footprint have become pressing concerns. With the increasing share of renewable energy in a datacenter's mixed energy supply, shifting task execution to periods of high green-power availability is a promising strategy to reduce carbon emissions. However, in heterogeneous computing environments, the power consumption of compute nodes in a datacenter can also vary. In practice, workloads submitted to datacenters are often not isolated tasks, but entire workflows consisting of interdependent tasks with precedence constraints. A further challenge arises from the fact that carbon emission reductions must typically be achieved under strict workflow deadlines. In this work, we show that the problem posed by these challenges for the scheduler is NP-hard and admits no constant-factor approximation even for the uni-processor case. Motivated by this hardness, we present a novel algorithm CWM that combines carbon-aware mapping and scheduling to construct feasible solutions. Our approach integrates dynamic programming with efficient heuristics to exploit renewable energy availability and infrastructure heterogeneity. To assess the quality of the new algorithm, we evaluate it against the state-of-the-art approach CaWoSched and show that CWM achieves significant reductions in terms of carbon emissions in experiments. In particular, we are able to achieve a median carbon cost reduction of 42% over the best version of CaWoSched when the deadline is two times the makespan of a carbon-agnostic baseline. Note that CaWoSched itself already reduces the carbon-agnostic baseline by 36%.

翻译：随着数据中心规模的持续扩展，其能耗及由此产生的碳足迹已成为紧迫问题。随着数据中心混合能源供应中可再生能源占比的不断提升，将任务执行迁移至绿色能源高可用时段是减少碳排放的有效策略。然而，在异构计算环境中，数据中心内计算节点的功耗亦存在差异。实践中，提交至数据中心的工作负载往往并非孤立任务，而是由具有优先约束关系的相互依赖任务组成的完整工作流。更严峻的挑战在于，碳减排目标通常需在严格的工作流截止期限内实现。本研究表明，调度器面临这些挑战所产生的问题是NP难的，即便在单处理器情况下也不存在常数因子近似算法。受此难度启发，我们提出新型算法CWM，该算法融合碳感知映射与调度以构建可行解。该方法将动态规划与高效启发式策略相结合，充分利用可再生能源可用性与基础设施异构性。为评估新算法质量，我们将其与当前最先进方法CaWoSched进行对比实验，结果表明CWM在碳排放方面实现了显著降低。当截止期限为碳无关基准调度长度两倍时，我们相对CaWoSched最优版本实现了中位数碳成本42%的降幅。值得注意的是，CaWoSched本身已较碳无关基准降低了36%的碳排放。