From 2a98bc18ea34dbf15f261a0df37080e588a189d1 Mon Sep 17 00:00:00 2001 From: slaren <2141330+slaren@users.noreply.github.com> Date: Tue, 28 Mar 2023 20:06:03 +0200 Subject: [PATCH] ggml : add AVX2 implementation of quantize_row_q4_1 (#515) * Add AVX2 implementation of quantize_row_q4_1 * Actually use AVX2 * Make quantize_row_q4_1 static Co-authored-by: Georgi Gerganov --------- Co-authored-by: Georgi Gerganov --- ggml.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 89 insertions(+), 2 deletions(-) diff --git a/ggml.c b/ggml.c index ea7277895..222d199be 100644 --- a/ggml.c +++ b/ggml.c @@ -688,7 +688,7 @@ static void quantize_row_q4_0(const float * restrict x, void * restrict vy, int #endif } -static void quantize_row_q4_1(const float * restrict x, void * restrict vy, int k) { +static void quantize_row_q4_1_reference(const float * restrict x, void * restrict vy, int k) { assert(k % QK == 0); const int nb = k / QK; @@ -729,6 +729,93 @@ static void quantize_row_q4_1(const float * restrict x, void * restrict vy, int } } +static void quantize_row_q4_1(const float * restrict x, void * restrict vy, int k) { + assert(k % QK == 0); + +#if defined(__AVX2__) + const int nb = k / QK; + + block_q4_1 * restrict y = vy; + + for (int i = 0; i < nb; i++) { + // Load elements into 4 AVX vectors + __m256 v0 = _mm256_loadu_ps( x ); + __m256 v1 = _mm256_loadu_ps( x + 8 ); + __m256 v2 = _mm256_loadu_ps( x + 16 ); + __m256 v3 = _mm256_loadu_ps( x + 24 ); + x += 32; + + // Compute max for the block + __m256 vmax; + vmax = _mm256_max_ps( v0, v1 ); + vmax = _mm256_max_ps( vmax, v2 ); + vmax = _mm256_max_ps( vmax, v3 ); + + __m128 max4 = _mm_max_ps( _mm256_extractf128_ps( vmax, 1 ), _mm256_castps256_ps128( vmax ) ); + max4 = _mm_max_ps( max4, _mm_movehl_ps( max4, max4 ) ); + max4 = _mm_max_ss( max4, _mm_movehdup_ps( max4 ) ); + const float maxScalar = _mm_cvtss_f32( max4 ); + + // Compute min for the block + __m256 vmin; + vmin = _mm256_min_ps( v0, v1 ); + vmin = _mm256_min_ps( vmin, v2 ); + vmin = _mm256_min_ps( vmin, v3 ); + + __m128 min4 = _mm_min_ps( _mm256_extractf128_ps( vmin, 1 ), _mm256_castps256_ps128( vmin ) ); + min4 = _mm_min_ps( min4, _mm_movehl_ps( min4, min4 ) ); + min4 = _mm_min_ss( min4, _mm_movehdup_ps( min4 ) ); + const float minScalar = _mm_cvtss_f32( min4 ); + + // Quantize these floats + const float d = (maxScalar - minScalar) / ((1 << 4) - 1); + const float id = d ? 1.0f/d : 0.0f; + + y[i].m = minScalar; + y[i].d = d; + + // x = (x-min)*id + const __m256 mul = _mm256_set1_ps( id ); + const __m256 off = _mm256_set1_ps( minScalar ); + v0 = _mm256_mul_ps( _mm256_sub_ps( v0, off ), mul ); + v1 = _mm256_mul_ps( _mm256_sub_ps( v1, off ), mul ); + v2 = _mm256_mul_ps( _mm256_sub_ps( v2, off ), mul ); + v3 = _mm256_mul_ps( _mm256_sub_ps( v3, off ), mul ); + + // Round to nearest integer + v0 = _mm256_round_ps( v0, _MM_ROUND_NEAREST ); + v1 = _mm256_round_ps( v1, _MM_ROUND_NEAREST ); + v2 = _mm256_round_ps( v2, _MM_ROUND_NEAREST ); + v3 = _mm256_round_ps( v3, _MM_ROUND_NEAREST ); + + // Convert floats to integers + __m256i i0 = _mm256_cvtps_epi32( v0 ); + __m256i i1 = _mm256_cvtps_epi32( v1 ); + __m256i i2 = _mm256_cvtps_epi32( v2 ); + __m256i i3 = _mm256_cvtps_epi32( v3 ); + + // Convert int32 to int16 + i0 = _mm256_packs_epi32( i0, i1 ); // 0, 1, 2, 3, 8, 9, 10, 11, 4, 5, 6, 7, 12, 13, 14, 15 + i2 = _mm256_packs_epi32( i2, i3 ); // 16, 17, 18, 19, 24, 25, 26, 27, 20, 21, 22, 23, 28, 29, 30, 31 + // Convert int16 to int8 + i0 = _mm256_packs_epi16( i0, i2 ); // 0, 1, 2, 3, 8, 9, 10, 11, 16, 17, 18, 19, 24, 25, 26, 27, 4, 5, 6, 7, 12, 13, 14, 15, 20, 21, 22, 23, 28, 29, 30, 31 + + // We got our precious signed bytes, but the order is now wrong + // These AVX2 pack instructions process 16-byte pieces independently + // The following instruction is fixing the order + const __m256i perm = _mm256_setr_epi32( 0, 4, 1, 5, 2, 6, 3, 7 ); + i0 = _mm256_permutevar8x32_epi32( i0, perm ); + + // Compress the vector into 4 bit/value, and store + __m128i res = packNibbles( i0 ); + _mm_storeu_si128( ( __m128i* )y[i].qs, res ); + } +#else + // scalar + quantize_row_q4_1_reference(x, vy, k); +#endif +} + static void dequantize_row_q4_0(const void * restrict vx, float * restrict y, int k) { assert(k % QK == 0); const int nb = k / QK; @@ -10135,7 +10222,7 @@ size_t ggml_quantize_q4_1(const float * src, void * dst, int n, int k, int64_t * for (int j = 0; j < n; j += k) { block_q4_1 * restrict y = (block_q4_1 *)dst + j/QK; - quantize_row_q4_1(src + j, y, k); + quantize_row_q4_1_reference(src + j, y, k); for (int i = 0; i < nb; i++) { for (int l = 0; l < QK; l += 2) {