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c606c19101
* Slightly faster FA for bf16 KV cache ~2-3% sort of thing. Sadly, when we go beyond 8k tokens, the advantage kind of goes away. * Slightly faster FA for Q8_0 KV cache * FA: allow bf16 for V-cache with any supported K-cache E.g., -ctk q8_0 -ctv bf16 is slightly faster than -ctk q8_0 -ctv q8_0 on Zen4 for not too long context lengths (say, <= 4096). * FA: much better bf16 kv-cache speed for large contexts We now hit 122 t/s for LLaMA-3.1-8B (quantized as iq4_xs and run-time-repacked) with a context of 32768. IIRC, the previous best for such large context was ~90 t/s. Non-negligible improvement at 16384 and 8192 as well: 173.4 and 214 t/s. * FA: slightly better quantized kv-cache speed for large contexts E.g., for q8_0 and context of 32768, we are now at 113 t/s for LLaMA-3.1-8B. Also simplified the quantized K*Q multiplication. * Fix q8_0 KV cache when not using FA - WIP (AVX2) 1. We add new types GGML_TYPE_Q8_0_X4 and GGML_TYPE_Q8_1_X4, and use those to quantize activations for quants that use Q8_0 or Q8_1 as their vec_dot type. 2. We revert the changes to quantize_row_q8_0 and quantize_row_q8_1 3. We use GGML_TYPE_Q8_0_X4 and GGML_TYPE_Q8_1_X4 as the vec_dot type 4. We change the FA implementation to use GGML_TYPE_Q8_0 rather than GGML_TYPE_Q8_0_X4 as the K and V types 5. We change the expected type to GGML_TYPE_Q8_0_X4/GGML_TYPE_Q8_1_X4 in iqk_mul_mat Also added an optimization in ggml_compute_forward_mul_mat when ne12*ne13 > 1 (K*Q and V*softmax(K*Q)) to process n12*ne13/GCD(n12*ne13, nthread) threads simultaneously using nthread/GCD(n12*ne13, nthread) threads per head. This results in a non-negligible performance gain for large contexts. Question: why is it not allowed to use quantized V-cache when not using FA? * Fix q8_0 KV cache when not using FA - NEON * Fix AVX2 Again the issue with _mm256_maddubs_epi16 overflowing that I keep forgetting. * FA: don't use large Q steps on AVX2 for fp16 K-cache * On Zen4 it is also better to not use large Q steps for fp16 K-cache --------- Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>