Enable AVX-VNNI 256-bit path for IQ4_NL R4 matmul#1467
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ikawrakow merged 1 commit intoikawrakow:mainfrom Mar 20, 2026
Merged
Enable AVX-VNNI 256-bit path for IQ4_NL R4 matmul#1467ikawrakow merged 1 commit intoikawrakow:mainfrom
ikawrakow merged 1 commit intoikawrakow:mainfrom
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ikawrakow
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Mar 20, 2026
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IQ4_NL has a special kernel in repacked (R4) mode (mul_mat_iq4_nl_r4_q8_2).
It currently has a FANCY_SIMD path that requires AVX-512, here we update the fallback AVX2 path to have a conditionally VNNI accelerated path on AVX-VNNI CPUs.
Benchmarks
Model: Qwen3.5-2B IQ4_NL, pp512
rtr 0 (control - different kernel that is already VNNI optimized)
rtr 1 (runtime repack - uses the newly optimized kernel)
Big improvement here, though rtr 0 is still faster on my hardware for this quant.
Text generation QA
Text generation QA with llama-cli across multiple prompts shows bit-identical results. Full perplexity against wikitest-2 is unchanged as well (13.1025 +/- 0.09740).