Startot

Startot is a term used in performance analysis to denote the moment at which a process reaches a predefined portion of its total expected output, effectively marking the start of the total completion window. It is used to study early completion dynamics in distributed systems and batch processing, where cumulative output grows over time.

Etymology and scope: The word is a portmanteau of start and total and has no standardized definition across disciplines. In practice, startot is defined relative to a chosen output threshold, such as 50% or 90% of the anticipated total, which can vary by context.

Formalization: Let O(t) be the cumulative output produced by time t. The startot time s is defined as s = inf{ t : O(t) ≥ T }, where T is the threshold. In stochastic models, O(t) may be treated as a random process and s as a random variable with a distribution derived from the process.

Applications: Startot informs autoscaling decisions, capacity planning, and latency analysis by focusing on when a substantial portion of work has begun to materialize. It is used to benchmark architectures and to compare strategies for data processing pipelines.

Limitations: The usefulness of startot depends on the choice of threshold and the definition of what constitutes the "output" in a given context. It can be sensitive to measurement windows, aggregation, and variability across nodes, which can limit cross-system comparability.

See also: Latency, time to first output, end-to-end performance, autoscaling.