From 1af6f38b63186056c7296691e60d2102936f9fbd Mon Sep 17 00:00:00 2001 From: Iwan Kawrakow Date: Sun, 23 Jul 2023 15:24:37 +0300 Subject: [PATCH] Spped up Q4_K on CUDA GTX1660: 29.5 ms/t -> 25.6 ms/t RTX4080: 8.40 ms/t -> 8.25 ms/t --- ggml-cuda.cu | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-) diff --git a/ggml-cuda.cu b/ggml-cuda.cu index 1783a4688..2d8b052c7 100644 --- a/ggml-cuda.cu +++ b/ggml-cuda.cu @@ -169,7 +169,7 @@ typedef struct { } block_q3_K; //static_assert(sizeof(block_q3_K) == sizeof(ggml_fp16_t) + QK_K / 4 + QK_K / 8 + K_SCALE_SIZE, "wrong q3_K block size/padding"); -#define QR4_K 2 +#define QR4_K 4 #define QI4_K (QK_K / (4*QR4_K)) #ifdef GGML_QKK_64 typedef struct { @@ -1566,7 +1566,8 @@ static __device__ __forceinline__ float vec_dot_q4_K_q8_1( #if __CUDA_ARCH__ >= MIN_CC_DP4A // lowest compute capability for integer intrinsics const block_q4_K * bq4_K = (const block_q4_K *) vbq; - const int bq8_offset = QR4_K * (iqs / QI8_1); // 0, 2, 4, 6 + // iqs is in 0...15. bq8_offset = 2 * (iqs/4) -> bq8_offset = 0, 2, 4, 6 + const int bq8_offset = (QR4_K/2) * (iqs / (QI8_1/2)); float sumf_d = 0.0f; float sumf_m = 0.0f; @@ -1574,7 +1575,14 @@ static __device__ __forceinline__ float vec_dot_q4_K_q8_1( const float d = bq4_K->d; const float dmin = bq4_K->dmin; - const int v = *((int *) &bq4_K->qs[sizeof(int) * iqs]); + // iqs = 0....3 -> bq8_offset = 0, want q4_offset = 0, 4, 8, 12 + // iqs = 4....7 -> bq8_offset = 2, want q4_offset = 32, 36, 40, 44 + // iqs = 8...11 -> bq8_offset = 4, want q4_offset = 64, 68, 72, 76 + // iqs = 12..15 -> bq8_offset = 6, want q4_offset = 96, 100, 104, 108 + + const int * q4 = (const int *)(bq4_K->qs + 16 * bq8_offset + 4 * (iqs%4)); + const int v1 = q4[0]; + const int v2 = q4[4]; const uint16_t * scales = (const uint16_t *)bq4_K->scales; uint16_t aux[2]; @@ -1589,16 +1597,22 @@ static __device__ __forceinline__ float vec_dot_q4_K_q8_1( const uint8_t * sc = (const uint8_t *)aux; const uint8_t * m = sc + 2; - for (int i = 0; i < QR4_K; ++i) { + for (int i = 0; i < QR4_K/2; ++i) { const block_q8_1 * bq8i = bq8_1 + bq8_offset + i; - const int ui = *((int*) &bq8i->qs[sizeof(int) * (iqs % QI8_1)]); const float d8i = bq8i->d; + const int * q8 = (const int *)bq8i->qs + (iqs%4); + const int ui1 = q8[0]; + const int ui2 = q8[4]; - const int vi = (v >> (4*i)) & 0x0F0F0F0F; + const int vi1 = (v1 >> (4*i)) & 0x0F0F0F0F; + const int vi2 = (v2 >> (4*i)) & 0x0F0F0F0F; - sumf_d += d8i * (__dp4a(vi, ui, 0) * sc[i]); // SIMD dot product - sumf_m += d8i * (__dp4a(0x01010101, ui, 0) * m[i]); // multiply constant part of q4_K with sum of q8_1 values + const int dot1 = __dp4a(vi2, ui2, __dp4a(vi1, ui1, 0)); + const int dot2 = __dp4a(0x01010101, ui2, __dp4a(0x01010101, ui1, 0)); + + sumf_d += d8i * (dot1 * sc[i]); // SIMD dot product + sumf_m += d8i * (dot2 * m[i]); // multiply constant part of q4_K with sum of q8_1 values } return d*sumf_d - dmin*sumf_m;