Dual 3090 Qwen3.8-27B: DFlash2 Speed Test and Full Config Guide

Old_Ad_6033 · reddit · 2026-08-29

A Redditor shared a full recipe for running the Qwen3.8-27B INT4 model on dual RTX 3090s (24GB). Using a stack of vLLM 0.28.0, LMCache, and DFlash2, the setup leverages NVMe as a Level 2 KV cache to support 256k context length. Benchmarks show that with DFlash2 enabled, decode speed for Code tasks hits 268 tok/s (3.8× speedup) and real agent jobs reach 165 tok/s. The author detailed the environment specs, LMCache server startup commands, and vLLM launch parameters, noting that specific patches are required to prevent cache corruption.

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