dusterbloom: perf(models): fused MoE gate+up — 3→2 expert matmuls per layer#12
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dusterbloom: perf(models): fused MoE gate+up — 3→2 expert matmuls per layer#12dusterbloom wants to merge 3 commits intomainfrom
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SwitchMlpWeights::forward_gather_fused() lazy-concatenates gate+up weights on first call, then dispatches a single gather_qmm instead of two separate calls. FfnBlock::forward() now routes through the fused path instead of forward_gather_global_sort(). Measured on 35B-A3B-3bit M4 base: - S=1 decode: 27ms → 17ms (−37%) - S=16 verify: 253ms → 112ms (−56%) - MoE/layer at K=1: 0.47ms (down from ~0.68ms) Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
Reflow `let fw/fs/fb = ops::concatenate_axis(..)` from broken-line indentation back onto single lines so `cargo fmt --all -- --check` passes in CI.
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Two errors flagged by `-D clippy::doc-markdown` and `-D clippy::cast-sign-loss`/`-D clippy::as-conversions`: - Backtick `MoE` and `gather_qmm` in the `fused_gate_up` doc comment. - Replace `top_k as u32` with the same `u32::try_from(top_k).map_err(...)` pattern already used by `forward_gather_global_sort`.
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Summary
SwitchMlpWeights::forward_gather_fused()lazy-concatenates gate+up weights on first call, then dispatches a singlegather_qmminstead of two separate calls.FfnBlock::forward()now routes through the fused path instead offorward_gather_global_sort().Numbers (35B-A3B-3bit on M4 base)
Test plan
cargo check -p higgs-models— cleancargo test -p higgs-models --lib qwen3_next::— 71 passed, 0 failed (includes newtest_moe_gate_up_fusion_parity)cargo run -p higgs-bench --release --bin bench_decode -- --model <qwen3_5_moe-key>— A/B against main on a Qwen3.5-MoE checkpointcargo clippy -p higgs-models— cleanNotes
crates/higgs-models/src/qwen3_next.rs(+175 / −9)