This Redis latency benchmark measures how long HotKV, Redis, Valkey and Dragonfly take to answer at a fixed request rate. Our earlier benchmarks measured throughput, and a reader rightly pointed out that throughput is not everything. So we held the load constant, raised it step by step, and recorded the median (p50) and the 99th percentile (p99) at each step. We also measured pub/sub delivery time.

In short. In this Redis latency benchmark on AWS, HotKV and Dragonfly both held 1.6 million GETs per second, Redis with 8 I/O threads held about 0.8 million, Valkey with 8 I/O threads about 0.4 million, and single-thread Redis and Valkey about 0.2 million. From 200,000 to 1.6 million requests per second HotKV's p99 stayed between 0.59 and 0.76 ms, against 0.71 to 1.48 ms for Dragonfly. At light load the multi-threaded products tied on p99, and pub/sub delivery was a tie.

Why we ran a Redis latency benchmark at a fixed rate

A throughput test pushes a server as hard as it will go and reports how much it served.…