5 steps to triage vLLM performance
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A diagnostic workflow for triaging vLLM inference performance issues in production. Covers five steps: isolating latency symptoms (TTFT vs ITL), detecting server saturation via queue metrics, evaluating VRAM and KV cache health, analyzing request sequence lengths, and reviewing distributed inference strategies. Includes concrete Prometheus queries, log examples, and remediation paths such as quantization (FP8), speculative decoding, tensor parallelism tuning, and right-sizing models. Emphasizes defining workload goals (throughput vs latency vs bursty) before diving into metrics.
Table of contents
Before you start: Define what success looks like1. Isolate the symptom: TTFT vs. ITL2. Detect server saturation3. Evaluate VRAM and KV cache health4. Analyze request sequence lengths5. Review distributed inference strategyWhat's next66 Impressions