mirror of https://github.com/hpcaitech/ColossalAI
110 lines
4.8 KiB
Python
110 lines
4.8 KiB
Python
import torch
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try:
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import triton
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import triton.language as tl
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HAS_TRITON = True
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except ImportError:
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HAS_TRITON = False
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print("please install triton from https://github.com/openai/triton")
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if HAS_TRITON:
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'''
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this kernel function is modified from https://triton-lang.org/main/getting-started/tutorials/03-matrix-multiplication.html
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'''
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@triton.jit
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def qkv_gemm_4d_kernel(
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a_ptr,
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b_ptr,
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c_ptr,
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M,
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N,
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K,
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stride_ab,
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stride_ah,
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stride_am,
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stride_ak,
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stride_bb,
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stride_bh,
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stride_bk,
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stride_bn,
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stride_cb,
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stride_ch,
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stride_cm,
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stride_cn,
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scale,
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# Meta-parameters
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BLOCK_SIZE_M : tl.constexpr = 64,
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BLOCK_SIZE_N : tl.constexpr = 32,
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BLOCK_SIZE_K : tl.constexpr = 32,
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GROUP_SIZE_M : tl.constexpr = 8,
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):
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r""" A kernel function which is used to do batch-matmul for Q*K^T or score_matrix * V for attention layer,
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where score_matrix is softmax(Q*V^T/sqrt(hidden_size))
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Args:
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a_ptr(torch.Tensor): pointer to input tensor array (bs, M, h, K) or (bs, h, M, K)
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b_ptr(torch.Tensor): pointer to input tensor array (bs, N, h, K) or (bs, h, N, K)
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c_ptr(torch.Tensor): pointer to output tensor array (bs, M, h, N) or (bs, h, M, N)
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stride_ab(tl.constexpr): stride for bs-dimention for tensor array A
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stride_ah(tl.constexpr): stride for h-dimention for tensor array A
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stride_am(tl.constexpr): stride for m-dimention for tensor array A
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stride_ak(tl.constexpr): stride for k-dimention for tensor array A
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stride_bb(tl.constexpr): stride for bs-dimention for tensor array B
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stride_bh(tl.constexpr): stride for h-dimention for tensor array B
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stride_bk(tl.constexpr): stride for k-dimention for tensor array B
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stride_bn(tl.constexpr): stride for n-dimention for tensor array B
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stride_cb(tl.constexpr): stride for bs-dimention for tensor array output
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stride_ch(tl.constexpr): stride for h-dimention for tensor array output
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stride_cm(tl.constexpr): stride for m-dimention for tensor array output
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stride_cn(tl.constexpr): stride for n-dimention for tensor array output
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BLOCK_SIZE_M : tiling size for M-dimension of tensor Array a
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BLOCK_SIZE_N : tiling size for N-dimension of tensor Array b
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BLOCK_SIZE_K : tiling size for K-dimension of a and b
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GROUP_SIZE_M : group size for reducing cache miss, more details:
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"""
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num_pid_m = tl.cdiv(M, BLOCK_SIZE_M)
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num_pid_n = tl.cdiv(N, BLOCK_SIZE_N)
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batch = tl.program_id(axis = 0)
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head = tl.program_id(axis = 1)
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pid = tl.program_id(axis = 2)
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# the following is from tutorial: https://triton-lang.org/main/getting-started/tutorials/03-matrix-multiplication.html
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num_pid_in_group = GROUP_SIZE_M * num_pid_n
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group_id = pid // num_pid_in_group
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first_pid_m = group_id * GROUP_SIZE_M
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group_size_m = min(num_pid_m - first_pid_m, GROUP_SIZE_M)
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pid_m = first_pid_m + (pid % group_size_m)
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pid_n = (pid % num_pid_in_group) // group_size_m
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offs_am = pid_m * BLOCK_SIZE_M + tl.arange(0, BLOCK_SIZE_M)
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offs_bn = pid_n * BLOCK_SIZE_N + tl.arange(0, BLOCK_SIZE_N)
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offs_k = tl.arange(0, BLOCK_SIZE_K)
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a_ptrs = (a_ptr + batch * stride_ab + head * stride_ah +
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(offs_am[:, None] * stride_am + offs_k[None, :] * stride_ak))
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b_ptrs = (b_ptr + batch * stride_bb + head * stride_bh +
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(offs_k[:, None] * stride_bk + offs_bn[None, :] * stride_bn))
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accumulator = tl.zeros((BLOCK_SIZE_M, BLOCK_SIZE_N), dtype=tl.float32)
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for k in range(0, K, BLOCK_SIZE_K):
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a_mask = (offs_am[:, None] < M) & (offs_k[None, :] + k < K)
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b_mask = (offs_k[:, None] + k < K) & (offs_bn[None, :] < N)
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a = tl.load(a_ptrs, mask=a_mask, other=0.)
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b = tl.load(b_ptrs, mask=b_mask, other=0.)
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accumulator += tl.dot(a, b)
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a_ptrs += BLOCK_SIZE_K * stride_ak
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b_ptrs += BLOCK_SIZE_K * stride_bk
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accumulator = accumulator.to(c_ptr.dtype.element_ty)
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if scale > 0:
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accumulator = accumulator * scale.to(c_ptr.dtype.element_ty)
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offs_accumu_m = pid_m * BLOCK_SIZE_M + tl.arange(0, BLOCK_SIZE_M)
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offs_accumu_n = pid_n * BLOCK_SIZE_N + tl.arange(0, BLOCK_SIZE_N)
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c_ptrs = (c_ptr + batch * stride_cb + head * stride_ch + stride_cm * offs_accumu_m[:, None] +
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stride_cn * offs_accumu_n[None, :])
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accumulator_mask = (offs_accumu_m[:, None] < M) & (offs_accumu_n[None, :] < N)
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tl.store(c_ptrs, accumulator, mask=accumulator_mask)
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