NVLink multicast unsupported on Blackwell Confidential Computing causes 61% performance regression on SGLang Qwen3.5 397
What changed
TRUTH SOCIAL: NVLINK MULTICAST IS NOT SUPPORTED ON BLACKWELL "CONFIDENTIAL COMPUTING" LEADING TO 61% PERFORMANCE REGRESSION ON SGLANG QWEN3.5 397B ACCORDING TO @VERDACLOUD 'S RECENT GITHUB TICKET. NVIDIA'S "CONFIDENTIAL COMPUTING" IS COMPLETE SLOP AS IN ADDITION HOPPER'S CONFIDENTIAL COMPUTING HAD FULLY UNENCRYPTED NVLINK ACCORDING TO NVIDIA'S OWN "NVIDIA SECURE AI WITH BLACKWELL AND HOPPER GPUS" WHITEPAPER. — VIA @SEMIANALYSIS_