Files
StarPilot/tinygrad_repo/extra/thunder/amd/fa_bwd_pre.cpp
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firestar5683 22a8575199 Vendor dependencies and resources for standalone builds
Keep official openpilot ancestry and dependency licenses. Store resources directly in Git, remove LFS setup requirements, and leave the downloadable big model outside the source tree.
2026-10-03 21:01:18 +00:00

92 lines
3.7 KiB
C++

#include "kittens.cuh"
#ifndef ATTN_B
constexpr int ATTN_B = 16; // batch size
#endif
#ifndef ATTN_H
constexpr int ATTN_H = 64; // number of query heads
#endif
#ifndef ATTN_H_KV
constexpr int ATTN_H_KV = 8; // number of key/value heads (for GQA)
#endif
constexpr int GROUP_SIZE = ATTN_H / ATTN_H_KV; // queries per KV head group
#ifndef ATTN_N
constexpr int ATTN_N = 1024; // sequence length
#endif
#ifndef ATTN_D
constexpr int ATTN_D = 128; // dimension
#endif
constexpr int STEP_QO = 64; // block size for QO
constexpr int BLOCK_SIZE_KV = 256; // block size for KV
constexpr int SLICE_QO = 32;
constexpr int DOT_SLICE_QO = 16;
constexpr int WARP_SIZE_KV = 64; // warp size for KV
#define NUM_WARPS 4
#define NUM_THREADS (kittens::WARP_THREADS * NUM_WARPS)
using G = kittens::group<NUM_WARPS>;
using namespace kittens;
template<int D, typename T=bf16, typename L=row_l, typename S=rt_16x32_s> using qo_tile = rt<T, DOT_SLICE_QO, D, L, S>;
template<int D, typename T=bf16, typename L=row_l, typename S=rt_16x32_s> using kv_tile = rt<T, WARP_SIZE_KV, D, L, S>;
template<int D, typename T=bf16, typename L=row_l, typename S=rt_16x32_s> using qo_tile_T_dq = rt<T, 32, 16, L, S>;
template<int D, typename T=bf16, typename L=row_l, typename S=rt_16x32_s> using qo_tile_dq = rt<T, 16, 32, L, S>;
template<int D, typename T=bf16, typename L=row_l, typename S=rt_16x32_s> using kv_tile_T = rt<T, D, WARP_SIZE_KV, L, S>;
template<int D, typename T=float, typename L=col_l, typename S=rt_16x16_s> using attn_tile = rt<T, DOT_SLICE_QO, WARP_SIZE_KV, L, S>;
template<int D, typename T=bf16, typename L=col_l, typename S=rt_32x16_s> using attn_tile_T = rt<T, WARP_SIZE_KV, DOT_SLICE_QO, L, S>;
template<int D, typename T=bf16, typename L=col_l, typename S=rt_32x16_s> using attn_tile_T_dq = rt<T, 256, 16, L, S>;
template<int D, typename T=bf16, typename L=row_l, typename S=rt_16x32_s> using kv_tile_dq = rt<T, 256, 32, L, S>;
template<int D> struct attn_prep_globals {
gl<bf16, -1, -1, -1, -1> Og;
gl<bf16, -1, -1, -1, -1> dOg;
gl<float, -1, -1, -1, -1> delta;
dim3 grid() { return dim3(ATTN_B, ATTN_H, ATTN_N / (DOT_SLICE_QO * NUM_WARPS)); }
dim3 block() { return dim3(NUM_THREADS); }
size_t dynamic_shared_memory() { return MAX_SHARED_MEMORY; }
};
template<int D> __launch_bounds__(NUM_THREADS, 1)
__global__ void attend_prep_ker(float *delta_ptr, bf16 *dq_ptr, bf16 *O_ptr, bf16 *dO_ptr) {
gl<float, -1, -1, -1, -1> delta{delta_ptr, ATTN_B, ATTN_H, 1, ATTN_N};
gl<bf16, -1, -1, -1, -1> dQg{dq_ptr, ATTN_B, ATTN_H, ATTN_N, ATTN_D};
gl<bf16, -1, -1, -1, -1> Og{O_ptr, ATTN_B, ATTN_N, ATTN_H, ATTN_D};
gl<bf16, -1, -1, -1, -1> dOg{dO_ptr, ATTN_B, ATTN_N, ATTN_H, ATTN_D};
attn_prep_globals<D> g{Og, dOg, delta};
const int batch_idx = blockIdx.x;
const int head_idx = blockIdx.y;
const int seq_idx = blockIdx.z;
const int warpid = kittens::warpid();
qo_tile<D, bf16, row_l, rt_16x32_s> dO, O;
qo_tile<D, float, row_l, rt_16x32_s> dO_float, O_float;
typename qo_tile<D, float, row_l, rt_16x32_s>::col_vec delta_vec;
load<1>(dO, g.dOg, {batch_idx, seq_idx * NUM_WARPS + warpid, head_idx, 0});
load<1>(O, g.Og, {batch_idx, seq_idx * NUM_WARPS + warpid, head_idx, 0});
copy(O_float, O);
copy(dO_float, dO);
// Δ_i = row_sum(dO ⊙ O)
mul(dO_float, dO_float, O_float);
row_sum(delta_vec, dO_float);
store(g.delta, delta_vec, {batch_idx, head_idx, 0, seq_idx * NUM_WARPS + warpid});
// Zero out dq
qo_tile<D, bf16, row_l, rt_16x32_s> dQ_zero;
zero(dQ_zero);
store<2>(dQg, dQ_zero, {batch_idx, head_idx, seq_idx * NUM_WARPS + warpid, 0});
}
template __global__ void attend_prep_ker<ATTN_D>(float *delta_ptr, bf16 *dq_ptr, bf16 *O_ptr, bf16 *dO_ptr);