How to Benchmark LLM Inference Performance: TTFT, ITL, and Throughput Metrics

When deploying large language models to production, measuring performance accurately is critical. Whether you're using vLLM, SGLang, TensorRT-LLM, or a custom inference stack, you need to understand: Throughput : How many requests per second can your system handle? Latency metrics : Time to First Token (TTFT), Inter-Token Latency (ITL), and end-to-end latency Token generation speed : Tokens per second under different concurrency levels Tail latency : P95 and P99 values that affect user experienc