SLI (Service Level Indicator)
A quantitative metric that measures the level of service being provided, serving as the concrete measurement against which SLOs are evaluated, such as request latency or error rate.
SLIs are the raw measurements that feed into SLO evaluation. Common SLIs include availability (percentage of successful requests), latency (request duration at a given percentile), throughput (requests processed per second), and error rate (percentage of failed requests). The SLI is the number you measure; the SLO is the target you set for that number.
Good SLIs are directly tied to user experience. Measuring server CPU utilization is not a useful SLI because users do not experience CPU utilization. Measuring the percentage of page loads that complete under 2 seconds is a useful SLI because it directly reflects what users experience. The closer the SLI is to the user's actual experience, the more useful it is for decision-making.
For AI features, effective SLIs might include time-to-first-token for streaming responses, percentage of responses that pass quality filters, embedding generation latency, and vector search recall accuracy. These measurements create a quantitative foundation for evaluating whether your AI features meet the reliability and quality standards your users expect.
Related Terms
A/B Testing
A controlled experiment comparing two or more variants to determine which performs better on a defined metric, using statistical methods to ensure reliable results.
Feature Flag
A software mechanism that enables or disables features at runtime without deploying new code, used for gradual rollouts, A/B testing, and targeting specific user segments.
MLOps
The set of practices combining machine learning, DevOps, and data engineering to reliably deploy, monitor, and maintain ML models in production.
Model Serving
The infrastructure and systems that host trained ML models and handle inference requests in production, optimizing for latency, throughput, and cost.
Semantic Search
Search that understands the meaning and intent behind a query rather than just matching keywords, typically powered by embedding-based similarity comparison.
CI/CD (Continuous Integration / Continuous Deployment)
An automated software practice where code changes are continuously integrated into a shared repository, tested, and deployed to production, reducing manual intervention and accelerating delivery cycles.