Decomposing Temporal and Job-Induced Dynamics for Probabilistic Computing Workload Forecasting via Graph-Conditioned Dual-Branch Diffusion

Workload forecasting is a fundamental task to realizing electricity-computing synergy in modern data centers, where operational planning must account for the risk induced by fluctuating computing demand. Yet production workloads exhibit substantial volatility, making deterministic point forecasts insufficient for uncertainty-aware decision making. Existing methods mainly model workload uncertainty from temporal correlations in utilization traces, overlooking the job-induced cross-machine dependencies shaped by the scheduling layer. We empirically find that workload volatility exhibits structured and time-varying cross-machine patterns whose strength aligns with job co-occurrence. This observation motivates GD-Diff, a job-aware graph-conditioned diffusion framework for probabilistic workload forecasting. GD-Diff constructs a job-induced weighted dynamic graph from scheduling logs, transforming job co-occurrence into time-varying inter-machine dependencies. Built on this graph, GD-Diff uses a dual-branch noise prediction network within the diffusion process, where the temporal branch captures regular temporal evolution and the graph branch models job-induced dynamics. Experiments on Alibaba and Google cluster traces show that GD-Diff achieves state-of-the-art performance in both point and probabilistic forecasting, and ablation studies further validate the job-induced dynamic graph and dual-branch architecture. The code is available at \url{https://anonymous.4open.science/r/GD-Diff-F5E8/}.