Running on 2x DGX Spark (GB10) via SGLang β€” recipe + 4 day-0 fixes

#2
by randomllama - opened

Got this drafter serving GLM-5.3-Flash (LibertAIDAI NVFP4) on 2x DGX Spark (GB10, sm_121), SGLang TP=2, using the PR #36507 branch stack (incl. the #36708 capture adapter).

Measured (warmed, temp 0, n=5 medians, 800 tok): 27.6 tok/s code decode vs 14.7 no-spec on the same stack = 1.88x (prose 1.41x). Accept len up to 5.6 of the 8-token block during code decode β€” consistent with the card's expectations.

Four GB10-specific issues had to be fixed to get here (multi-node SGLANG_HOST_IP hang; mamba/KDA state pool needs per_req*(1+D) + ratio~5 with this drafter attached; DSA tilelang smem overflow at the 8-token verify shape; residual=None crash in the capture adapter during graph capture). All documented with patches and probes:

https://github.com/beastllama/GLM-5.3-Flash-DFlash2-SGLang-2x-DGX-Spark

Note for GB10 users: we do not yet claim bit-identical greedy outputs on this stack (1 near-tie token flip observed in a 5-prompt temp-0 comparison; full matrix in progress).

Follow-up with a finding your team may want: on our stack (SGLang PR #36507 branch, 2x GB10 sm_121, LibertAIDAI NVFP4 target, tilelang DSA, bf16 KV), DFlash2-on is NOT bit-identical to speculative-off at temperature 0. A 20-prompt matrix capturing both content and reasoning_content: 1/20 exactly identical, 19/20 diverge at near-tie tokens that cascade through long reasoning traces. Output quality is preserved (all correctness gates passed) - this is exactness, not quality. The card's "greedy output matches the target model" does not reproduce here; candidate causes are verify-path numerics on sm_121 or NVFP4 quant interaction - we couldn't isolate which. Full data + method: https://github.com/beastllama/GLM-5.3-Flash-DFlash2-SGLang-2x-DGX-Spark (RESULTS.md, G6 section). Happy to run diagnostics if useful.

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