Aneto: Predicting System Performance by Exploiting Cross-Workload Regularity
Predicting how a workload responds to a change in memory technology requires estimating how much of each cache miss actually stalls the processor. Obtaining this stall fraction accurately has traditionally demanded detailed simulation, repeated measurements, or heavy profiling. One-shot alternatives exist but sacrifice accuracy. We observe that hardware counters from a single native run suffice to infer the stall fraction without simulation. Across more than 100 diverse workloads spanning integer, floating-point, graph, and AI benchmarks, the relationship between CPI and the maximum memory stall per instruction follows a predictable pattern on each microarchitecture. Aneto is a mechanistic-empirical regression model that exploits this observation. Once fitted on a machine across a small set of reference workloads, the model estimates the performance-latency sensitivity of any new workload from a single run, enabling first-order CPI prediction under any memory configuration. Across six machines and two simulators, Aneto reaches 2x lower CPI error than the best prior one-shot predictor. We validate the predictions directly against hardware measurements on an ARM server, from local DDR to HBM and up to ~3x the baseline memory penalty, where the median CPI error is 12.7% and the 90th percentile 35.9%. At an 8x memory-latency extrapolation beyond the reach of direct measurement, Aneto agrees with a reference model on Zen 5 to within 14.6% at the median and 41% at the 90th percentile. Additionally, Aneto provides qualitative insights into workloads and architectures.