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Update for fix.
Browse files- README.md +1 -1
- flash_attn_triton.py +0 -861
- modeling.py +0 -4
- requirements.txt +2 -0
- tokenizers.py +0 -1
README.md
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sdk: gradio
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sdk_version: 4.1.1
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app_file:
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---
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sdk: gradio
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sdk_version: 4.1.1
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app_file: webui.py
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flash_attn_triton.py
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"""
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Copied from https://github.com/HazyResearch/flash-attention/blob/eff9fe6b8076df59d64d7a3f464696738a3c7c24/flash_attn/flash_attn_triton.py
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update imports to use 'triton_pre_mlir'
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*Experimental* implementation of FlashAttention in Triton.
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Tested with triton==2.0.0.dev20221202.
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Triton 2.0 has a new backend (MLIR) but seems like it doesn't yet work for head dimensions
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other than 64:
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https://github.com/openai/triton/blob/d376020f90002757eea3ea9475d4f7cfc2ec5ead/python/triton/ops/flash_attention.py#L207
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We'll update this implementation with the new Triton backend once this is fixed.
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We use the FlashAttention implementation from Phil Tillet a starting point.
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https://github.com/openai/triton/blob/master/python/tutorials/06-fused-attention.py
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Changes:
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- Implement both causal and non-causal attention.
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- Implement both self-attention and cross-attention.
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- Support arbitrary seqlens (not just multiples of 128), for both forward and backward.
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- Support all head dimensions up to 128 (not just 16, 32, 64, 128), for both forward and backward.
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- Support attention bias.
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- Speed up the forward pass a bit, and only store the LSE instead of m and l.
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- Make the backward for d=128 much faster by reducing register spilling.
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- Optionally parallelize the backward pass across seqlen_k, to deal with the case of
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small batch size * nheads.
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Caution:
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- This is an *experimental* implementation. The forward pass should be quite robust but
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I'm not 100% sure that the backward pass doesn't have race conditions (due to the Triton compiler).
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- This implementation has only been tested on A100.
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- If you plan to use headdim other than 64 and 128, you should test for race conditions
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(due to the Triton compiler), as done in tests/test_flash_attn.py
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"test_flash_attn_triton_race_condition". I've tested and fixed many race conditions
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for different head dimensions (40, 48, 64, 128, 80, 88, 96), but I'm still not 100% confident
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that there are none left for other head dimensions.
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Differences between this Triton version and the CUDA version:
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- Triton version doesn't support dropout.
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- Triton forward is generally faster than CUDA forward, while Triton backward is
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generally slower than CUDA backward. Overall Triton forward + backward is slightly slower
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than CUDA forward + backward.
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- Triton version doesn't support different sequence lengths in a batch (i.e., RaggedTensor/NestedTensor).
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- Triton version supports attention bias, while CUDA version doesn't.
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"""
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import math
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import torch
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import os
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import triton_pre_mlir as triton
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import triton_pre_mlir.compiler
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import triton_pre_mlir.language as tl
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import functools
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import subprocess
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if 'CONDA_PREFIX' in os.environ and 'CUDA_HOME' not in os.environ:
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os.environ['CUDA_HOME'] = os.environ['CONDA_PREFIX']
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@functools.lru_cache()
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def libcuda_dirs():
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libs = subprocess.check_output(["ldconfig", "-p"]).decode()
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# each line looks like the following:
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# libcuda.so.1 (libc6,x86-64) => /lib/x86_64-linux-gnu/libcuda.so.1
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locs = [line.split()[-1] for line in libs.splitlines() if "libcuda.so" in line]
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dirs = [os.path.dirname(loc) for loc in locs]
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msg = 'libcuda.so cannot found!\n'
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if locs:
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msg += 'Possible files are located at %s.' % str(locs)
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msg += 'Please create a symlink of libcuda.so to any of the file.'
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assert any(os.path.exists(os.path.join(path, 'libcuda.so')) for path in dirs), msg
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return dirs
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triton_pre_mlir.compiler.libcuda_dirs = libcuda_dirs
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# Disabling autotune for now, set num_warps=4 if headdim=64 and num_warps=8 if headdim=128
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# @triton.autotune(
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# configs=[
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# triton.Config({"BLOCK_M": 128, "BLOCK_N": 128}, num_warps=4, num_stages=1),
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# # This config has a race condition when EVEN_M == False, disabling it for now.
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# # triton.Config({"BLOCK_M": 64, "BLOCK_N": 64}, num_warps=4, num_stages=1),
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# ],
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# key=['CACHE_KEY_SEQLEN_Q', 'CACHE_KEY_SEQLEN_K', 'BIAS_TYPE', 'IS_CAUSAL', 'BLOCK_HEADDIM']
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# )
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@triton.heuristics(
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{
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"EVEN_M": lambda args: args["seqlen_q"] % args["BLOCK_M"] == 0,
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"EVEN_N": lambda args: args["seqlen_k"] % args["BLOCK_N"] == 0,
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"EVEN_HEADDIM": lambda args: args["headdim"] == args["BLOCK_HEADDIM"],
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}
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)
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@triton.jit
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def _fwd_kernel(
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Q, K, V, Bias, Out,
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Lse, TMP, # NOTE: TMP is a scratchpad buffer to workaround a compiler bug
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softmax_scale,
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stride_qb, stride_qh, stride_qm,
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stride_kb, stride_kh, stride_kn,
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stride_vb, stride_vh, stride_vn,
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stride_bb, stride_bh, stride_bm,
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stride_ob, stride_oh, stride_om,
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nheads, seqlen_q, seqlen_k, seqlen_q_rounded, headdim,
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CACHE_KEY_SEQLEN_Q, CACHE_KEY_SEQLEN_K,
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BIAS_TYPE: tl.constexpr,
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IS_CAUSAL: tl.constexpr,
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BLOCK_HEADDIM: tl.constexpr,
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EVEN_M: tl.constexpr, EVEN_N: tl.constexpr, EVEN_HEADDIM: tl.constexpr,
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BLOCK_M: tl.constexpr, BLOCK_N: tl.constexpr,
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):
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start_m = tl.program_id(0)
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off_hb = tl.program_id(1)
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off_b = off_hb // nheads
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off_h = off_hb % nheads
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# off_b = tl.program_id(1)
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# off_h = tl.program_id(2)
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# off_hb = off_b * nheads + off_h
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# initialize offsets
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offs_m = start_m * BLOCK_M + tl.arange(0, BLOCK_M)
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offs_n = tl.arange(0, BLOCK_N)
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offs_d = tl.arange(0, BLOCK_HEADDIM)
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# Initialize pointers to Q, K, V
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# Adding parenthesis around indexing might use int32 math instead of int64 math?
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# https://github.com/openai/triton/issues/741
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# I'm seeing a tiny bit of difference (5-7us)
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q_ptrs = Q + off_b * stride_qb + off_h * stride_qh + (offs_m[:, None] * stride_qm + offs_d[None, :])
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k_ptrs = K + off_b * stride_kb + off_h * stride_kh + (offs_n[:, None] * stride_kn + offs_d[None, :])
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v_ptrs = V + off_b * stride_vb + off_h * stride_vh + (offs_n[:, None] * stride_vn + offs_d[None, :])
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if BIAS_TYPE == 'vector':
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b_ptrs = Bias + off_b * stride_bb + off_h * stride_bh + offs_n
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elif BIAS_TYPE == 'matrix':
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b_ptrs = Bias + off_b * stride_bb + off_h * stride_bh + (offs_m[:, None] * stride_bm + offs_n[None, :])
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# initialize pointer to m and l
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t_ptrs = TMP + off_hb * seqlen_q_rounded + offs_m
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lse_i = tl.zeros([BLOCK_M], dtype=tl.float32) - float("inf")
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m_i = tl.zeros([BLOCK_M], dtype=tl.float32) - float("inf")
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acc_o = tl.zeros([BLOCK_M, BLOCK_HEADDIM], dtype=tl.float32)
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# load q: it will stay in SRAM throughout
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# [2022-10-30] TD: Triton bug - in the case of EVEN_M=True and EVEN_N=False, if we just call
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# tl.load(q_ptrs), we get the wrong output!
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if EVEN_M & EVEN_N:
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if EVEN_HEADDIM:
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q = tl.load(q_ptrs)
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else:
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q = tl.load(q_ptrs, mask=offs_d[None, :] < headdim, other=0.0)
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else:
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if EVEN_HEADDIM:
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q = tl.load(q_ptrs, mask=offs_m[:, None] < seqlen_q, other=0.0)
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else:
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q = tl.load(q_ptrs, mask=(offs_m[:, None] < seqlen_q) & (offs_d[None, :] < headdim),
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other=0.0)
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# loop over k, v and update accumulator
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end_n = seqlen_k if not IS_CAUSAL else tl.minimum((start_m + 1) * BLOCK_M, seqlen_k)
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for start_n in range(0, end_n, BLOCK_N):
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start_n = tl.multiple_of(start_n, BLOCK_N)
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# -- compute qk ----
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if EVEN_N & EVEN_M: # If we just do "if EVEN_N", there seems to be some race condition
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if EVEN_HEADDIM:
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k = tl.load(k_ptrs + start_n * stride_kn)
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else:
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k = tl.load(k_ptrs + start_n * stride_kn, mask=offs_d[None, :] < headdim, other=0.0)
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else:
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if EVEN_HEADDIM:
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k = tl.load(k_ptrs + start_n * stride_kn, mask=(start_n + offs_n)[:, None] < seqlen_k,
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other=0.0)
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else:
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k = tl.load(k_ptrs + start_n * stride_kn,
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mask=((start_n + offs_n)[:, None] < seqlen_k) & (offs_d[None, :] < headdim),
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other=0.0)
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qk = tl.zeros([BLOCK_M, BLOCK_N], dtype=tl.float32)
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qk += tl.dot(q, k, trans_b=True)
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# Trying to combine the two masks seem to make the result wrong
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if not EVEN_N: # Need to mask out otherwise the softmax is wrong
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qk += tl.where((start_n + offs_n)[None, :] < seqlen_k, 0, float("-inf"))
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if IS_CAUSAL:
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qk += tl.where(offs_m[:, None] >= (start_n + offs_n)[None, :], 0, float("-inf"))
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if BIAS_TYPE != 'none':
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if BIAS_TYPE == 'vector':
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if EVEN_N:
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bias = tl.load(b_ptrs + start_n).to(tl.float32)
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else:
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bias = tl.load(b_ptrs + start_n, mask=(start_n + offs_n) < seqlen_k, other=0.0).to(tl.float32)
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bias = bias[None, :]
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elif BIAS_TYPE == 'matrix':
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if EVEN_M & EVEN_N:
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bias = tl.load(b_ptrs + start_n).to(tl.float32)
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else:
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bias = tl.load(b_ptrs + start_n,
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mask=(offs_m[:, None] < seqlen_q)
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& ((start_n + offs_n)[None, :] < seqlen_k),
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other=0.0).to(tl.float32)
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# Slightly faster to multiply the softmax_scale in the tl.exp below since the compiler
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# can then fuse the mult and add into an fma instruction. But if we have bias we need to
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# to multiply with softmax_scale here.
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qk = qk * softmax_scale + bias
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m_ij = tl.maximum(tl.max(qk, 1), lse_i)
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p = tl.exp(qk - m_ij[:, None])
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else:
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m_ij = tl.maximum(tl.max(qk, 1) * softmax_scale, lse_i)
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p = tl.exp(qk * softmax_scale - m_ij[:, None])
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l_ij = tl.sum(p, 1)
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# scale acc_o
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acc_o_scale = tl.exp(m_i - m_ij)
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# # -- update output accumulator --
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# BUG: have to store and immediately load
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tl.store(t_ptrs, acc_o_scale)
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acc_o_scale = tl.load(t_ptrs)
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acc_o = acc_o * acc_o_scale[:, None]
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# update acc_o
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if EVEN_N & EVEN_M: # If we just do "if EVEN_N", there seems to be some race condition
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if EVEN_HEADDIM:
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v = tl.load(v_ptrs + start_n * stride_vn)
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else:
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v = tl.load(v_ptrs + start_n * stride_vn, mask=offs_d[None, :] < headdim, other=0.0)
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else:
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if EVEN_HEADDIM:
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v = tl.load(v_ptrs + start_n * stride_vn, mask=(start_n + offs_n)[:, None] < seqlen_k,
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other=0.0)
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else:
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v = tl.load(v_ptrs + start_n * stride_vn,
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mask=((start_n + offs_n)[:, None] < seqlen_k) & (offs_d[None, :] < headdim),
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other=0.0)
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p = p.to(v.dtype)
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acc_o += tl.dot(p, v)
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# -- update statistics
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m_i = m_ij
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l_i_new = tl.exp(lse_i - m_ij) + l_ij
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lse_i = m_ij + tl.log(l_i_new)
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o_scale = tl.exp(m_i - lse_i)
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# BUG: have to store and immediately load
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tl.store(t_ptrs, o_scale)
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o_scale = tl.load(t_ptrs)
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acc_o = acc_o * o_scale[:, None]
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# rematerialize offsets to save registers
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start_m = tl.program_id(0)
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offs_m = start_m * BLOCK_M + tl.arange(0, BLOCK_M)
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# write back l and m
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lse_ptrs = Lse + off_hb * seqlen_q_rounded + offs_m
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tl.store(lse_ptrs, lse_i)
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# initialize pointers to output
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offs_d = tl.arange(0, BLOCK_HEADDIM)
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out_ptrs = Out + off_b * stride_ob + off_h * stride_oh + (offs_m[:, None] * stride_om + offs_d[None, :])
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if EVEN_M:
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if EVEN_HEADDIM:
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tl.store(out_ptrs, acc_o)
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else:
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tl.store(out_ptrs, acc_o, mask=offs_d[None, :] < headdim)
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else:
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if EVEN_HEADDIM:
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tl.store(out_ptrs, acc_o, mask=offs_m[:, None] < seqlen_q)
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else:
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tl.store(out_ptrs, acc_o,
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mask=(offs_m[:, None] < seqlen_q) & (offs_d[None, :] < headdim))
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-
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@triton.jit
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def _bwd_preprocess_do_o_dot(
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Out, DO, Delta,
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stride_ob, stride_oh, stride_om,
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stride_dob, stride_doh, stride_dom,
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nheads, seqlen_q, seqlen_q_rounded, headdim,
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BLOCK_M: tl.constexpr, BLOCK_HEADDIM: tl.constexpr,
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):
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start_m = tl.program_id(0)
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off_hb = tl.program_id(1)
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off_b = off_hb // nheads
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off_h = off_hb % nheads
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# initialize offsets
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offs_m = start_m * BLOCK_M + tl.arange(0, BLOCK_M)
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offs_d = tl.arange(0, BLOCK_HEADDIM)
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# load
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o = tl.load(Out + off_b * stride_ob + off_h * stride_oh + offs_m[:, None] * stride_om + offs_d[None, :],
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mask=(offs_m[:, None] < seqlen_q) & (offs_d[None, :] < headdim), other=0.0).to(tl.float32)
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do = tl.load(DO + off_b * stride_dob + off_h * stride_doh + offs_m[:, None] * stride_dom + offs_d[None, :],
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mask=(offs_m[:, None] < seqlen_q) & (offs_d[None, :] < headdim), other=0.0).to(tl.float32)
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delta = tl.sum(o * do, axis=1)
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# write-back
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tl.store(Delta + off_hb * seqlen_q_rounded + offs_m, delta)
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@triton.jit
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def _bwd_store_dk_dv(
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dk_ptrs, dv_ptrs, dk, dv, offs_n, offs_d, seqlen_k, headdim,
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EVEN_M: tl.constexpr, EVEN_N: tl.constexpr, EVEN_HEADDIM: tl.constexpr,
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):
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# [2022-11-01] TD: Same bug. In the case of EVEN_N=True and EVEN_M=False,
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# if we just call tl.store(dv_ptrs), there's a race condition
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293 |
-
if EVEN_N & EVEN_M:
|
294 |
-
if EVEN_HEADDIM:
|
295 |
-
tl.store(dv_ptrs, dv)
|
296 |
-
tl.store(dk_ptrs, dk)
|
297 |
-
else:
|
298 |
-
tl.store(dv_ptrs, dv, mask=offs_d[None, :] < headdim)
|
299 |
-
tl.store(dk_ptrs, dk, mask=offs_d[None, :] < headdim)
|
300 |
-
else:
|
301 |
-
if EVEN_HEADDIM:
|
302 |
-
tl.store(dv_ptrs, dv, mask=offs_n[:, None] < seqlen_k)
|
303 |
-
tl.store(dk_ptrs, dk, mask=offs_n[:, None] < seqlen_k)
|
304 |
-
else:
|
305 |
-
tl.store(dv_ptrs, dv, mask=(offs_n[:, None] < seqlen_k) & (offs_d[None, :] < headdim))
|
306 |
-
tl.store(dk_ptrs, dk, mask=(offs_n[:, None] < seqlen_k) & (offs_d[None, :] < headdim))
|
307 |
-
|
308 |
-
|
309 |
-
@triton.jit
|
310 |
-
def _bwd_kernel_one_col_block(
|
311 |
-
start_n,
|
312 |
-
Q, K, V, Bias,
|
313 |
-
DO, DQ, DK, DV,
|
314 |
-
LSE, D,
|
315 |
-
softmax_scale,
|
316 |
-
stride_qm, stride_kn, stride_vn, stride_bm,
|
317 |
-
stride_dom, stride_dqm, stride_dkn, stride_dvn,
|
318 |
-
seqlen_q, seqlen_k, headdim,
|
319 |
-
ATOMIC_ADD: tl.constexpr,
|
320 |
-
BIAS_TYPE: tl.constexpr,
|
321 |
-
IS_CAUSAL: tl.constexpr,
|
322 |
-
BLOCK_HEADDIM: tl.constexpr,
|
323 |
-
EVEN_M: tl.constexpr, EVEN_N: tl.constexpr, EVEN_HEADDIM: tl.constexpr,
|
324 |
-
BLOCK_M: tl.constexpr, BLOCK_N: tl.constexpr,
|
325 |
-
):
|
326 |
-
# We need to make sure begin_m is a multiple of BLOCK_M (not BLOCK_N)
|
327 |
-
begin_m = 0 if not IS_CAUSAL else ((start_n * BLOCK_N) // BLOCK_M) * BLOCK_M
|
328 |
-
# initialize row/col offsets
|
329 |
-
offs_qm = begin_m + tl.arange(0, BLOCK_M)
|
330 |
-
offs_n = start_n * BLOCK_N + tl.arange(0, BLOCK_N)
|
331 |
-
offs_m = tl.arange(0, BLOCK_M)
|
332 |
-
offs_d = tl.arange(0, BLOCK_HEADDIM)
|
333 |
-
# initialize pointers to value-like data
|
334 |
-
q_ptrs = Q + (offs_qm[:, None] * stride_qm + offs_d[None, :])
|
335 |
-
k_ptrs = K + (offs_n[:, None] * stride_kn + offs_d[None, :])
|
336 |
-
v_ptrs = V + (offs_n[:, None] * stride_vn + offs_d[None, :])
|
337 |
-
do_ptrs = DO + (offs_qm[:, None] * stride_dom + offs_d[None, :])
|
338 |
-
dq_ptrs = DQ + (offs_qm[:, None] * stride_dqm + offs_d[None, :])
|
339 |
-
if BIAS_TYPE == 'vector':
|
340 |
-
b_ptrs = Bias + offs_n
|
341 |
-
elif BIAS_TYPE == 'matrix':
|
342 |
-
b_ptrs = Bias + (offs_qm[:, None] * stride_bm + offs_n[None, :])
|
343 |
-
# initialize dv and dk
|
344 |
-
dv = tl.zeros([BLOCK_N, BLOCK_HEADDIM], dtype=tl.float32)
|
345 |
-
dk = tl.zeros([BLOCK_N, BLOCK_HEADDIM], dtype=tl.float32)
|
346 |
-
# There seems to be some problem with Triton pipelining that makes results wrong for
|
347 |
-
# headdim=64, seqlen=(113, 255), bias_type='matrix'. In this case the for loop
|
348 |
-
# may have zero step, and pipelining with the bias matrix could screw it up.
|
349 |
-
# So we just exit early.
|
350 |
-
if begin_m >= seqlen_q:
|
351 |
-
dv_ptrs = DV + (offs_n[:, None] * stride_dvn + offs_d[None, :])
|
352 |
-
dk_ptrs = DK + (offs_n[:, None] * stride_dkn + offs_d[None, :])
|
353 |
-
_bwd_store_dk_dv(dk_ptrs, dv_ptrs, dk, dv, offs_n, offs_d, seqlen_k, headdim,
|
354 |
-
EVEN_M=EVEN_M, EVEN_N=EVEN_N, EVEN_HEADDIM=EVEN_HEADDIM)
|
355 |
-
return
|
356 |
-
# k and v stay in SRAM throughout
|
357 |
-
# [2022-10-30] TD: Same bug as the fwd. In the case of EVEN_N=True and EVEN_M=False,
|
358 |
-
# if we just call tl.load(k_ptrs), we get the wrong output!
|
359 |
-
if EVEN_N & EVEN_M:
|
360 |
-
if EVEN_HEADDIM:
|
361 |
-
k = tl.load(k_ptrs)
|
362 |
-
v = tl.load(v_ptrs)
|
363 |
-
else:
|
364 |
-
k = tl.load(k_ptrs, mask=offs_d[None, :] < headdim, other=0.0)
|
365 |
-
v = tl.load(v_ptrs, mask=offs_d[None, :] < headdim, other=0.0)
|
366 |
-
else:
|
367 |
-
if EVEN_HEADDIM:
|
368 |
-
k = tl.load(k_ptrs, mask=offs_n[:, None] < seqlen_k, other=0.0)
|
369 |
-
v = tl.load(v_ptrs, mask=offs_n[:, None] < seqlen_k, other=0.0)
|
370 |
-
else:
|
371 |
-
k = tl.load(k_ptrs, mask=(offs_n[:, None] < seqlen_k) & (offs_d[None, :] < headdim),
|
372 |
-
other=0.0)
|
373 |
-
v = tl.load(v_ptrs, mask=(offs_n[:, None] < seqlen_k) & (offs_d[None, :] < headdim),
|
374 |
-
other=0.0)
|
375 |
-
# loop over rows
|
376 |
-
num_block_m = tl.cdiv(seqlen_q, BLOCK_M)
|
377 |
-
for start_m in range(begin_m, num_block_m * BLOCK_M, BLOCK_M):
|
378 |
-
start_m = tl.multiple_of(start_m, BLOCK_M)
|
379 |
-
offs_m_curr = start_m + offs_m
|
380 |
-
# load q, k, v, do on-chip
|
381 |
-
# Same bug as below. Otherwise gives wrong result for headdim=40, seqlen=(128, 117)
|
382 |
-
if EVEN_M & EVEN_HEADDIM:
|
383 |
-
q = tl.load(q_ptrs)
|
384 |
-
else:
|
385 |
-
if EVEN_HEADDIM:
|
386 |
-
q = tl.load(q_ptrs, mask=offs_m_curr[:, None] < seqlen_q, other=0.0)
|
387 |
-
else:
|
388 |
-
q = tl.load(q_ptrs, mask=(offs_m_curr[:, None] < seqlen_q)
|
389 |
-
& (offs_d[None, :] < headdim), other=0.0)
|
390 |
-
# recompute p = softmax(qk, dim=-1).T
|
391 |
-
qk = tl.dot(q, k, trans_b=True)
|
392 |
-
# Trying to combine the two masks seem to make the result wrong
|
393 |
-
if not EVEN_N: # Need to mask out otherwise the softmax is wrong
|
394 |
-
qk = tl.where(offs_n[None, :] < seqlen_k, qk, float("-inf"))
|
395 |
-
if IS_CAUSAL:
|
396 |
-
qk = tl.where(offs_m_curr[:, None] >= (offs_n[None, :]), qk, float("-inf"))
|
397 |
-
if BIAS_TYPE != 'none':
|
398 |
-
tl.debug_barrier() # Race condition otherwise
|
399 |
-
if BIAS_TYPE == 'vector':
|
400 |
-
if EVEN_N:
|
401 |
-
bias = tl.load(b_ptrs).to(tl.float32)
|
402 |
-
else:
|
403 |
-
bias = tl.load(b_ptrs, mask=offs_n < seqlen_k, other=0.0).to(tl.float32)
|
404 |
-
bias = bias[None, :]
|
405 |
-
elif BIAS_TYPE == 'matrix':
|
406 |
-
if EVEN_M & EVEN_N:
|
407 |
-
bias = tl.load(b_ptrs).to(tl.float32)
|
408 |
-
else:
|
409 |
-
bias = tl.load(b_ptrs,
|
410 |
-
mask=(offs_m_curr[:, None] < seqlen_q)
|
411 |
-
& (offs_n[None, :] < seqlen_k),
|
412 |
-
other=0.0).to(tl.float32)
|
413 |
-
qk = qk * softmax_scale + bias
|
414 |
-
# There seems to be a race condition when headdim=48/96, and dq, dk, dv are wrong.
|
415 |
-
# Also wrong for headdim=64.
|
416 |
-
if not (EVEN_M & EVEN_HEADDIM):
|
417 |
-
tl.debug_barrier()
|
418 |
-
lse_i = tl.load(LSE + offs_m_curr)
|
419 |
-
if BIAS_TYPE == 'none':
|
420 |
-
p = tl.exp(qk * softmax_scale - lse_i[:, None])
|
421 |
-
else:
|
422 |
-
p = tl.exp(qk - lse_i[:, None])
|
423 |
-
# compute dv
|
424 |
-
# [2022-10-30] TD: A Triton bug: if EVEN_M=True and EVEN_HEADDIM=False, if we call
|
425 |
-
# do = tl.load(do_ptrs, mask=offs_d[None, :] < headdim, other=0.0), we get wrong outputs
|
426 |
-
# in the case of headdim=48/96, seqlen_q & seqlen_k >= 512. If headdim=40 or seqlen < 512,
|
427 |
-
# the output is correct.
|
428 |
-
if EVEN_M & EVEN_HEADDIM:
|
429 |
-
do = tl.load(do_ptrs)
|
430 |
-
else:
|
431 |
-
# [2022-11-01] TD: Triton bug, there's a race condition if we just use m_mask and not d_mask.
|
432 |
-
do = tl.load(do_ptrs, mask=(offs_m_curr[:, None] < seqlen_q)
|
433 |
-
& (offs_d[None, :] < headdim), other=0.0)
|
434 |
-
# if EVEN_M:
|
435 |
-
# if EVEN_HEADDIM:
|
436 |
-
# do = tl.load(do_ptrs)
|
437 |
-
# else:
|
438 |
-
# do = tl.load(do_ptrs, mask=offs_d[None, :] < headdim, other=0.0)
|
439 |
-
# else:
|
440 |
-
# if EVEN_HEADDIM:
|
441 |
-
# do = tl.load(do_ptrs, mask=offs_m_curr[:, None] < seqlen_q, other=0.0)
|
442 |
-
# else:
|
443 |
-
# do = tl.load(do_ptrs, mask=(offs_m_curr[:, None] < seqlen_q)
|
444 |
-
# & (offs_d[None, :] < headdim), other=0.0)
|
445 |
-
dv += tl.dot(p.to(do.dtype), do, trans_a=True)
|
446 |
-
# compute dp = dot(v, do)
|
447 |
-
# There seems to be a race condition when headdim=48/96, and dq, dk are wrong.
|
448 |
-
# Also wrong for headdim=128, seqlen=(108, 256), and ATOMIC_ADD=True
|
449 |
-
# Also wrong for headdim=64, seqlen=(1023, 1024), and ATOMIC_ADD=False
|
450 |
-
if not (EVEN_M & EVEN_HEADDIM):
|
451 |
-
tl.debug_barrier()
|
452 |
-
dp = tl.dot(do, v, trans_b=True)
|
453 |
-
# There's a race condition for headdim=48
|
454 |
-
if not EVEN_HEADDIM:
|
455 |
-
tl.debug_barrier()
|
456 |
-
# compute ds = p * (dp - delta[:, None])
|
457 |
-
# Putting the subtraction after the dp matmul (instead of before) is slightly faster
|
458 |
-
Di = tl.load(D + offs_m_curr)
|
459 |
-
# Converting ds to q.dtype here reduces register pressure and makes it much faster
|
460 |
-
# for BLOCK_HEADDIM=128
|
461 |
-
ds = (p * (dp - Di[:, None]) * softmax_scale).to(q.dtype)
|
462 |
-
# compute dk = dot(ds.T, q)
|
463 |
-
dk += tl.dot(ds, q, trans_a=True)
|
464 |
-
# compute dq
|
465 |
-
if not (EVEN_M & EVEN_HEADDIM): # Otherewise there's a race condition when BIAS_TYPE='matrix'
|
466 |
-
tl.debug_barrier()
|
467 |
-
if not ATOMIC_ADD:
|
468 |
-
if EVEN_M & EVEN_HEADDIM: # Race condition if we just do EVEN_M
|
469 |
-
dq = tl.load(dq_ptrs, eviction_policy="evict_last")
|
470 |
-
dq += tl.dot(ds, k)
|
471 |
-
tl.store(dq_ptrs, dq, eviction_policy="evict_last")
|
472 |
-
else:
|
473 |
-
if EVEN_HEADDIM:
|
474 |
-
dq = tl.load(dq_ptrs, mask=offs_m_curr[:, None] < seqlen_q, other=0.0,
|
475 |
-
eviction_policy="evict_last")
|
476 |
-
dq += tl.dot(ds, k)
|
477 |
-
tl.store(dq_ptrs, dq, mask=offs_m_curr[:, None] < seqlen_q,
|
478 |
-
eviction_policy="evict_last")
|
479 |
-
else:
|
480 |
-
dq = tl.load(dq_ptrs,
|
481 |
-
mask=(offs_m_curr[:, None] < seqlen_q) & (offs_d[None, :] < headdim),
|
482 |
-
other=0.0, eviction_policy="evict_last")
|
483 |
-
dq += tl.dot(ds, k)
|
484 |
-
tl.store(dq_ptrs, dq,
|
485 |
-
mask=(offs_m_curr[:, None] < seqlen_q) & (offs_d[None, :] < headdim),
|
486 |
-
eviction_policy="evict_last")
|
487 |
-
else: # If we're parallelizing across the seqlen_k dimension
|
488 |
-
dq = tl.dot(ds, k)
|
489 |
-
if EVEN_M & EVEN_HEADDIM: # Race condition if we just do EVEN_M
|
490 |
-
tl.atomic_add(dq_ptrs, dq)
|
491 |
-
else:
|
492 |
-
if EVEN_HEADDIM:
|
493 |
-
tl.atomic_add(dq_ptrs, dq, mask=offs_m_curr[:, None] < seqlen_q)
|
494 |
-
else:
|
495 |
-
tl.atomic_add(dq_ptrs, dq,
|
496 |
-
mask=(offs_m_curr[:, None] < seqlen_q) & (offs_d[None, :] < headdim))
|
497 |
-
# increment pointers
|
498 |
-
dq_ptrs += BLOCK_M * stride_dqm
|
499 |
-
q_ptrs += BLOCK_M * stride_qm
|
500 |
-
do_ptrs += BLOCK_M * stride_dom
|
501 |
-
if BIAS_TYPE == 'matrix':
|
502 |
-
b_ptrs += BLOCK_M * stride_bm
|
503 |
-
# write-back
|
504 |
-
dv_ptrs = DV + (offs_n[:, None] * stride_dvn + offs_d[None, :])
|
505 |
-
dk_ptrs = DK + (offs_n[:, None] * stride_dkn + offs_d[None, :])
|
506 |
-
_bwd_store_dk_dv(dk_ptrs, dv_ptrs, dk, dv, offs_n, offs_d, seqlen_k, headdim,
|
507 |
-
EVEN_M=EVEN_M, EVEN_N=EVEN_N, EVEN_HEADDIM=EVEN_HEADDIM)
|
508 |
-
|
509 |
-
|
510 |
-
def init_to_zero(name):
|
511 |
-
return lambda nargs: nargs[name].zero_()
|
512 |
-
|
513 |
-
|
514 |
-
# TODO: Change BLOCK_M and BLOCK_N according to your GPU and num_warps according to headdim
|
515 |
-
@triton.autotune(
|
516 |
-
configs=[
|
517 |
-
triton.Config({"BLOCK_M": 64, "BLOCK_N": 64, "SEQUENCE_PARALLEL": False}, num_warps=4, num_stages=1, pre_hook=init_to_zero('DQ')),
|
518 |
-
triton.Config({"BLOCK_M": 64, "BLOCK_N": 64, "SEQUENCE_PARALLEL": True}, num_warps=4, num_stages=1, pre_hook=init_to_zero('DQ')),
|
519 |
-
# Other configs seem to give wrong results when seqlen_q % 128 != 0, disabling them for now
|
520 |
-
# # Kernel is buggy (give wrong result) if we set BLOCK_m=128, BLOCK_n=64, num_warps=*4*
|
521 |
-
# triton.Config({"BLOCK_M": 128, "BLOCK_N": 64, "SEQUENCE_PARALLEL": False}, num_warps=8, num_stages=1, pre_hook=init_to_zero('DQ')),
|
522 |
-
# triton.Config({"BLOCK_M": 128, "BLOCK_N": 64, "SEQUENCE_PARALLEL": True}, num_warps=8, num_stages=1, pre_hook=init_to_zero('DQ')),
|
523 |
-
# triton.Config({"BLOCK_M": 64, "BLOCK_N": 64, "SEQUENCE_PARALLEL": False}, num_warps=4, num_stages=1, pre_hook=init_to_zero('DQ')),
|
524 |
-
# triton.Config({"BLOCK_M": 64, "BLOCK_N": 64, "SEQUENCE_PARALLEL": True}, num_warps=4, num_stages=1, pre_hook=init_to_zero('DQ')),
|
525 |
-
],
|
526 |
-
key=['CACHE_KEY_SEQLEN_Q', 'CACHE_KEY_SEQLEN_K', 'BIAS_TYPE', 'IS_CAUSAL', 'BLOCK_HEADDIM'],
|
527 |
-
)
|
528 |
-
@triton.heuristics(
|
529 |
-
{
|
530 |
-
"EVEN_M": lambda args: args["seqlen_q"] % args["BLOCK_M"] == 0,
|
531 |
-
"EVEN_N": lambda args: args["seqlen_k"] % args["BLOCK_N"] == 0,
|
532 |
-
"EVEN_HEADDIM": lambda args: args["headdim"] == args["BLOCK_HEADDIM"],
|
533 |
-
}
|
534 |
-
)
|
535 |
-
@triton.jit
|
536 |
-
def _bwd_kernel(
|
537 |
-
Q, K, V, Bias,
|
538 |
-
DO, DQ, DK, DV,
|
539 |
-
LSE, D,
|
540 |
-
softmax_scale,
|
541 |
-
stride_qb, stride_qh, stride_qm,
|
542 |
-
stride_kb, stride_kh, stride_kn,
|
543 |
-
stride_vb, stride_vh, stride_vn,
|
544 |
-
stride_bb, stride_bh, stride_bm,
|
545 |
-
stride_dob, stride_doh, stride_dom,
|
546 |
-
stride_dqb, stride_dqh, stride_dqm,
|
547 |
-
stride_dkb, stride_dkh, stride_dkn,
|
548 |
-
stride_dvb, stride_dvh, stride_dvn,
|
549 |
-
nheads, seqlen_q, seqlen_k, seqlen_q_rounded, headdim,
|
550 |
-
CACHE_KEY_SEQLEN_Q, CACHE_KEY_SEQLEN_K,
|
551 |
-
BIAS_TYPE: tl.constexpr,
|
552 |
-
IS_CAUSAL: tl.constexpr,
|
553 |
-
BLOCK_HEADDIM: tl.constexpr,
|
554 |
-
SEQUENCE_PARALLEL: tl.constexpr,
|
555 |
-
EVEN_M: tl.constexpr, EVEN_N: tl.constexpr, EVEN_HEADDIM: tl.constexpr,
|
556 |
-
BLOCK_M: tl.constexpr, BLOCK_N: tl.constexpr,
|
557 |
-
):
|
558 |
-
off_hb = tl.program_id(1)
|
559 |
-
off_b = off_hb // nheads
|
560 |
-
off_h = off_hb % nheads
|
561 |
-
# offset pointers for batch/head
|
562 |
-
Q += off_b * stride_qb + off_h * stride_qh
|
563 |
-
K += off_b * stride_kb + off_h * stride_kh
|
564 |
-
V += off_b * stride_vb + off_h * stride_vh
|
565 |
-
DO += off_b * stride_dob + off_h * stride_doh
|
566 |
-
DQ += off_b * stride_dqb + off_h * stride_dqh
|
567 |
-
DK += off_b * stride_dkb + off_h * stride_dkh
|
568 |
-
DV += off_b * stride_dvb + off_h * stride_dvh
|
569 |
-
if BIAS_TYPE != 'none':
|
570 |
-
Bias += off_b * stride_bb + off_h * stride_bh
|
571 |
-
# pointer to row-wise quantities in value-like data
|
572 |
-
D += off_hb * seqlen_q_rounded
|
573 |
-
LSE += off_hb * seqlen_q_rounded
|
574 |
-
if not SEQUENCE_PARALLEL:
|
575 |
-
num_block_n = tl.cdiv(seqlen_k, BLOCK_N)
|
576 |
-
for start_n in range(0, num_block_n):
|
577 |
-
_bwd_kernel_one_col_block(
|
578 |
-
start_n,
|
579 |
-
Q, K, V, Bias,
|
580 |
-
DO, DQ, DK, DV,
|
581 |
-
LSE, D,
|
582 |
-
softmax_scale,
|
583 |
-
stride_qm, stride_kn, stride_vn, stride_bm,
|
584 |
-
stride_dom, stride_dqm, stride_dkn, stride_dvn,
|
585 |
-
seqlen_q, seqlen_k, headdim,
|
586 |
-
ATOMIC_ADD=False,
|
587 |
-
BIAS_TYPE=BIAS_TYPE,
|
588 |
-
IS_CAUSAL=IS_CAUSAL,
|
589 |
-
BLOCK_HEADDIM=BLOCK_HEADDIM,
|
590 |
-
EVEN_M=EVEN_M, EVEN_N=EVEN_N, EVEN_HEADDIM=EVEN_HEADDIM,
|
591 |
-
BLOCK_M=BLOCK_M, BLOCK_N=BLOCK_N
|
592 |
-
)
|
593 |
-
else:
|
594 |
-
start_n = tl.program_id(0)
|
595 |
-
_bwd_kernel_one_col_block(
|
596 |
-
start_n,
|
597 |
-
Q, K, V, Bias,
|
598 |
-
DO, DQ, DK, DV,
|
599 |
-
LSE, D,
|
600 |
-
softmax_scale,
|
601 |
-
stride_qm, stride_kn, stride_vn, stride_bm,
|
602 |
-
stride_dom, stride_dqm, stride_dkn, stride_dvn,
|
603 |
-
seqlen_q, seqlen_k, headdim,
|
604 |
-
ATOMIC_ADD=True,
|
605 |
-
BIAS_TYPE=BIAS_TYPE,
|
606 |
-
IS_CAUSAL=IS_CAUSAL,
|
607 |
-
BLOCK_HEADDIM=BLOCK_HEADDIM,
|
608 |
-
EVEN_M=EVEN_M, EVEN_N=EVEN_N, EVEN_HEADDIM=EVEN_HEADDIM,
|
609 |
-
BLOCK_M=BLOCK_M, BLOCK_N=BLOCK_N
|
610 |
-
)
|
611 |
-
|
612 |
-
|
613 |
-
def _flash_attn_forward(q, k, v, bias=None, causal=False, softmax_scale=None):
|
614 |
-
# shape constraints
|
615 |
-
batch, seqlen_q, nheads, d = q.shape
|
616 |
-
_, seqlen_k, _, _ = k.shape
|
617 |
-
assert k.shape == (batch, seqlen_k, nheads, d)
|
618 |
-
assert v.shape == (batch, seqlen_k, nheads, d)
|
619 |
-
assert d <= 128, 'FlashAttention only support head dimensions up to 128'
|
620 |
-
assert q.dtype == k.dtype == v.dtype, 'All tensors must have the same type'
|
621 |
-
assert q.dtype in [torch.float16, torch.bfloat16], 'Only support fp16 and bf16'
|
622 |
-
assert q.is_cuda and k.is_cuda and v.is_cuda
|
623 |
-
softmax_scale = softmax_scale or 1.0 / math.sqrt(d)
|
624 |
-
|
625 |
-
has_bias = bias is not None
|
626 |
-
bias_type = 'none'
|
627 |
-
if has_bias:
|
628 |
-
assert bias.dtype in [q.dtype, torch.float]
|
629 |
-
assert bias.is_cuda
|
630 |
-
assert bias.dim() == 4
|
631 |
-
if bias.stride(-1) != 1:
|
632 |
-
bias = bias.contiguous()
|
633 |
-
if bias.shape[2:] == (1, seqlen_k):
|
634 |
-
bias_type = 'vector'
|
635 |
-
elif bias.shape[2:] == (seqlen_q, seqlen_k):
|
636 |
-
bias_type = 'matrix'
|
637 |
-
else:
|
638 |
-
raise RuntimeError('Last 2 dimensions of bias must be (1, seqlen_k)'
|
639 |
-
' or (seqlen_q, seqlen_k)')
|
640 |
-
bias = bias.expand(batch, nheads, seqlen_q, seqlen_k)
|
641 |
-
bias_strides = (bias.stride(0), bias.stride(1), bias.stride(2)) if has_bias else (0, 0, 0)
|
642 |
-
|
643 |
-
seqlen_q_rounded = math.ceil(seqlen_q / 128) * 128
|
644 |
-
lse = torch.empty((batch, nheads, seqlen_q_rounded), device=q.device, dtype=torch.float32)
|
645 |
-
tmp = torch.empty((batch, nheads, seqlen_q_rounded), device=q.device, dtype=torch.float32)
|
646 |
-
o = torch.empty_like(q)
|
647 |
-
|
648 |
-
BLOCK_HEADDIM = max(triton.next_power_of_2(d), 16)
|
649 |
-
BLOCK = 128
|
650 |
-
num_warps = 4 if d <= 64 else 8
|
651 |
-
grid = lambda META: (triton.cdiv(seqlen_q, META["BLOCK_M"]), batch * nheads)
|
652 |
-
_fwd_kernel[grid](
|
653 |
-
q, k, v, bias, o,
|
654 |
-
lse, tmp,
|
655 |
-
softmax_scale,
|
656 |
-
q.stride(0), q.stride(2), q.stride(1),
|
657 |
-
k.stride(0), k.stride(2), k.stride(1),
|
658 |
-
v.stride(0), v.stride(2), v.stride(1),
|
659 |
-
*bias_strides,
|
660 |
-
o.stride(0), o.stride(2), o.stride(1),
|
661 |
-
nheads, seqlen_q, seqlen_k, seqlen_q_rounded, d,
|
662 |
-
seqlen_q // 32, seqlen_k // 32, # key for triton cache (limit number of compilations)
|
663 |
-
# Can't use kwargs here because triton autotune expects key to be args, not kwargs
|
664 |
-
# IS_CAUSAL=causal, BLOCK_HEADDIM=d,
|
665 |
-
bias_type, causal, BLOCK_HEADDIM,
|
666 |
-
BLOCK_M=BLOCK, BLOCK_N=BLOCK,
|
667 |
-
num_warps=num_warps,
|
668 |
-
num_stages=1,
|
669 |
-
)
|
670 |
-
return o, lse, softmax_scale # softmax_scale could have been updated
|
671 |
-
|
672 |
-
|
673 |
-
def _flash_attn_backward(do, q, k, v, o, lse, dq, dk, dv, bias=None, causal=False, softmax_scale=None):
|
674 |
-
# Make sure that the last dimension is contiguous
|
675 |
-
if do.stride(-1) != 1:
|
676 |
-
do = do.contiguous()
|
677 |
-
batch, seqlen_q, nheads, d = q.shape
|
678 |
-
_, seqlen_k, _, _ = k.shape
|
679 |
-
# assert d in {16, 32, 64, 128}
|
680 |
-
assert d <= 128
|
681 |
-
seqlen_q_rounded = math.ceil(seqlen_q / 128) * 128
|
682 |
-
assert lse.shape == (batch, nheads, seqlen_q_rounded)
|
683 |
-
assert q.stride(-1) == k.stride(-1) == v.stride(-1) == o.stride(-1) == 1
|
684 |
-
assert dq.stride(-1) == dk.stride(-1) == dv.stride(-1) == 1
|
685 |
-
softmax_scale = softmax_scale or 1.0 / math.sqrt(d)
|
686 |
-
# dq_accum = torch.zeros_like(q, dtype=torch.float32)
|
687 |
-
dq_accum = torch.empty_like(q, dtype=torch.float32)
|
688 |
-
delta = torch.empty_like(lse)
|
689 |
-
# delta = torch.zeros_like(lse)
|
690 |
-
|
691 |
-
BLOCK_HEADDIM = max(triton.next_power_of_2(d), 16)
|
692 |
-
grid = lambda META: (triton.cdiv(seqlen_q, META["BLOCK_M"]), batch * nheads)
|
693 |
-
_bwd_preprocess_do_o_dot[grid](
|
694 |
-
o, do, delta,
|
695 |
-
o.stride(0), o.stride(2), o.stride(1),
|
696 |
-
do.stride(0), do.stride(2), do.stride(1),
|
697 |
-
nheads, seqlen_q, seqlen_q_rounded, d,
|
698 |
-
BLOCK_M=128, BLOCK_HEADDIM=BLOCK_HEADDIM,
|
699 |
-
)
|
700 |
-
|
701 |
-
has_bias = bias is not None
|
702 |
-
bias_type = 'none'
|
703 |
-
if has_bias:
|
704 |
-
assert bias.dtype in [q.dtype, torch.float]
|
705 |
-
assert bias.is_cuda
|
706 |
-
assert bias.dim() == 4
|
707 |
-
assert bias.stride(-1) == 1
|
708 |
-
if bias.shape[2:] == (1, seqlen_k):
|
709 |
-
bias_type = 'vector'
|
710 |
-
elif bias.shape[2:] == (seqlen_q, seqlen_k):
|
711 |
-
bias_type = 'matrix'
|
712 |
-
else:
|
713 |
-
raise RuntimeError('Last 2 dimensions of bias must be (1, seqlen_k)'
|
714 |
-
' or (seqlen_q, seqlen_k)')
|
715 |
-
bias = bias.expand(batch, nheads, seqlen_q, seqlen_k)
|
716 |
-
bias_strides = (bias.stride(0), bias.stride(1), bias.stride(2)) if has_bias else (0, 0, 0)
|
717 |
-
|
718 |
-
# BLOCK_M = 128
|
719 |
-
# BLOCK_N = 64
|
720 |
-
# num_warps = 4
|
721 |
-
grid = lambda META: (triton.cdiv(seqlen_k, META["BLOCK_N"]) if META["SEQUENCE_PARALLEL"] else 1,
|
722 |
-
batch * nheads)
|
723 |
-
_bwd_kernel[grid](
|
724 |
-
q, k, v, bias,
|
725 |
-
do, dq_accum, dk, dv,
|
726 |
-
lse, delta,
|
727 |
-
softmax_scale,
|
728 |
-
q.stride(0), q.stride(2), q.stride(1),
|
729 |
-
k.stride(0), k.stride(2), k.stride(1),
|
730 |
-
v.stride(0), v.stride(2), v.stride(1),
|
731 |
-
*bias_strides,
|
732 |
-
do.stride(0), do.stride(2), do.stride(1),
|
733 |
-
dq_accum.stride(0), dq_accum.stride(2), dq_accum.stride(1),
|
734 |
-
dk.stride(0), dk.stride(2), dk.stride(1),
|
735 |
-
dv.stride(0), dv.stride(2), dv.stride(1),
|
736 |
-
nheads, seqlen_q, seqlen_k, seqlen_q_rounded, d,
|
737 |
-
seqlen_q // 32, seqlen_k // 32, # key for triton cache (limit number of compilations)
|
738 |
-
# Can't use kwargs here because triton autotune expects key to be args, not kwargs
|
739 |
-
# IS_CAUSAL=causal, BLOCK_HEADDIM=d,
|
740 |
-
bias_type, causal, BLOCK_HEADDIM,
|
741 |
-
# SEQUENCE_PARALLEL=False,
|
742 |
-
# BLOCK_M=BLOCK_M, BLOCK_N=BLOCK_N,
|
743 |
-
# num_warps=num_warps,
|
744 |
-
# num_stages=1,
|
745 |
-
)
|
746 |
-
dq.copy_(dq_accum)
|
747 |
-
|
748 |
-
|
749 |
-
class FlashAttnQKVPackedFunc(torch.autograd.Function):
|
750 |
-
|
751 |
-
@staticmethod
|
752 |
-
def forward(ctx, qkv, bias=None, causal=False, softmax_scale=None):
|
753 |
-
"""
|
754 |
-
qkv: (batch, seqlen, 3, nheads, headdim)
|
755 |
-
bias: optional, shape broadcastible to (batch, nheads, seqlen, seqlen).
|
756 |
-
For example, ALiBi mask for causal would have shape (1, nheads, 1, seqlen).
|
757 |
-
ALiBi mask for non-causal would have shape (1, nheads, seqlen, seqlen)
|
758 |
-
"""
|
759 |
-
# Make sure that the last dimension is contiguous
|
760 |
-
if qkv.stride(-1) != 1:
|
761 |
-
qkv = qkv.contiguous()
|
762 |
-
o, lse, ctx.softmax_scale = _flash_attn_forward(
|
763 |
-
qkv[:, :, 0], qkv[:, :, 1], qkv[:, :, 2], bias=bias, causal=causal,
|
764 |
-
softmax_scale=softmax_scale
|
765 |
-
)
|
766 |
-
ctx.save_for_backward(qkv, o, lse, bias)
|
767 |
-
ctx.causal = causal
|
768 |
-
return o
|
769 |
-
|
770 |
-
@staticmethod
|
771 |
-
def backward(ctx, do):
|
772 |
-
qkv, o, lse, bias = ctx.saved_tensors
|
773 |
-
assert not ctx.needs_input_grad[1], 'FlashAttention does not support bias gradient yet'
|
774 |
-
# Triton's autotune causes the Tensor._version to change, and so Pytorch autograd
|
775 |
-
# does a memcpy. To avoid this we run in inference_mode, which doesn't track the version.
|
776 |
-
with torch.inference_mode():
|
777 |
-
dqkv = torch.empty_like(qkv)
|
778 |
-
_flash_attn_backward(do, qkv[:, :, 0], qkv[:, :, 1], qkv[:, :, 2], o, lse,
|
779 |
-
dqkv[:, :, 0], dqkv[:, :, 1], dqkv[:, :, 2],
|
780 |
-
bias=bias, causal=ctx.causal, softmax_scale=ctx.softmax_scale)
|
781 |
-
return dqkv, None, None, None
|
782 |
-
|
783 |
-
|
784 |
-
flash_attn_qkvpacked_func = FlashAttnQKVPackedFunc.apply
|
785 |
-
|
786 |
-
|
787 |
-
class FlashAttnKVPackedFunc(torch.autograd.Function):
|
788 |
-
|
789 |
-
@staticmethod
|
790 |
-
def forward(ctx, q, kv, bias=None, causal=False, softmax_scale=None):
|
791 |
-
"""
|
792 |
-
q: (batch, seqlen_q, nheads, headdim)
|
793 |
-
kv: (batch, seqlen_k, 2, nheads, headdim)
|
794 |
-
bias: optional, shape broadcastible to (batch, nheads, seqlen_q, seqlen_k).
|
795 |
-
For example, ALiBi mask for causal would have shape (1, nheads, 1, seqlen_k).
|
796 |
-
ALiBi mask for non-causal would have shape (1, nheads, seqlen_q, seqlen_k)
|
797 |
-
"""
|
798 |
-
# Make sure that the last dimension is contiguous
|
799 |
-
q, kv = [x if x.stride(-1) == 1 else x.contiguous() for x in [q, kv]]
|
800 |
-
o, lse, ctx.softmax_scale = _flash_attn_forward(
|
801 |
-
q, kv[:, :, 0], kv[:, :, 1], bias=bias, causal=causal, softmax_scale=softmax_scale
|
802 |
-
)
|
803 |
-
ctx.save_for_backward(q, kv, o, lse, bias)
|
804 |
-
ctx.causal = causal
|
805 |
-
return o
|
806 |
-
|
807 |
-
@staticmethod
|
808 |
-
def backward(ctx, do):
|
809 |
-
q, kv, o, lse, bias = ctx.saved_tensors
|
810 |
-
if len(ctx.needs_input_grad) >= 3:
|
811 |
-
assert not ctx.needs_input_grad[2], 'FlashAttention does not support bias gradient yet'
|
812 |
-
# Triton's autotune causes the Tensor._version to change, and so Pytorch autograd
|
813 |
-
# does a memcpy. To avoid this we run in inference_mode, which doesn't track the version.
|
814 |
-
with torch.inference_mode():
|
815 |
-
dq = torch.empty_like(q)
|
816 |
-
dkv = torch.empty_like(kv)
|
817 |
-
_flash_attn_backward(do, q, kv[:, :, 0], kv[:, :, 1], o, lse,
|
818 |
-
dq, dkv[:, :, 0], dkv[:, :, 1],
|
819 |
-
bias=bias, causal=ctx.causal, softmax_scale=ctx.softmax_scale)
|
820 |
-
return dq, dkv, None, None, None
|
821 |
-
|
822 |
-
|
823 |
-
flash_attn_kvpacked_func = FlashAttnKVPackedFunc.apply
|
824 |
-
|
825 |
-
|
826 |
-
class FlashAttnFunc(torch.autograd.Function):
|
827 |
-
|
828 |
-
@staticmethod
|
829 |
-
def forward(ctx, q, k, v, bias=None, causal=False, softmax_scale=None):
|
830 |
-
"""
|
831 |
-
q: (batch_size, seqlen_q, nheads, headdim)
|
832 |
-
k, v: (batch_size, seqlen_k, nheads, headdim)
|
833 |
-
bias: optional, shape broadcastible to (batch, nheads, seqlen_q, seqlen_k).
|
834 |
-
For example, ALiBi mask for causal would have shape (1, nheads, 1, seqlen_k).
|
835 |
-
ALiBi mask for non-causal would have shape (1, nheads, seqlen_q, seqlen_k)
|
836 |
-
"""
|
837 |
-
# Make sure that the last dimension is contiguous
|
838 |
-
q, k, v = [x if x.stride(-1) == 1 else x.contiguous() for x in [q, k, v]]
|
839 |
-
o, lse, ctx.softmax_scale = _flash_attn_forward(
|
840 |
-
q, k, v, bias=bias, causal=causal, softmax_scale=softmax_scale
|
841 |
-
)
|
842 |
-
ctx.save_for_backward(q, k, v, o, lse, bias)
|
843 |
-
ctx.causal = causal
|
844 |
-
return o
|
845 |
-
|
846 |
-
@staticmethod
|
847 |
-
def backward(ctx, do):
|
848 |
-
q, k, v, o, lse, bias = ctx.saved_tensors
|
849 |
-
assert not ctx.needs_input_grad[3], 'FlashAttention does not support bias gradient yet'
|
850 |
-
# Triton's autotune causes the Tensor._version to change, and so Pytorch autograd
|
851 |
-
# does a memcpy. To avoid this we run in inference_mode, which doesn't track the version.
|
852 |
-
with torch.inference_mode():
|
853 |
-
dq = torch.empty_like(q)
|
854 |
-
dk = torch.empty_like(k)
|
855 |
-
dv = torch.empty_like(v)
|
856 |
-
_flash_attn_backward(do, q, k, v, o, lse, dq, dk, dv,
|
857 |
-
bias=bias, causal=ctx.causal, softmax_scale=ctx.softmax_scale)
|
858 |
-
return dq, dk, dv, None, None, None
|
859 |
-
|
860 |
-
|
861 |
-
flash_attn_func = FlashAttnFunc.apply
|
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|
modeling.py
CHANGED
@@ -3,11 +3,8 @@ from torch import nn
|
|
3 |
from dataclasses import dataclass
|
4 |
from enum import Enum
|
5 |
from typing import *
|
6 |
-
from flash_attn import flash_attn_func
|
7 |
-
from flash_attn_triton import flash_attn_func as flash_attn_func_triton
|
8 |
from math import ceil
|
9 |
|
10 |
-
|
11 |
class AttentionBackend(Enum):
|
12 |
Naive = 0
|
13 |
FlashAttentionCuda = 1
|
@@ -18,7 +15,6 @@ global_config = {
|
|
18 |
'attn_backend': AttentionBackend.Naive
|
19 |
}
|
20 |
|
21 |
-
|
22 |
@dataclass
|
23 |
class TransformerConfig:
|
24 |
vocab_size: int = -1,
|
|
|
3 |
from dataclasses import dataclass
|
4 |
from enum import Enum
|
5 |
from typing import *
|
|
|
|
|
6 |
from math import ceil
|
7 |
|
|
|
8 |
class AttentionBackend(Enum):
|
9 |
Naive = 0
|
10 |
FlashAttentionCuda = 1
|
|
|
15 |
'attn_backend': AttentionBackend.Naive
|
16 |
}
|
17 |
|
|
|
18 |
@dataclass
|
19 |
class TransformerConfig:
|
20 |
vocab_size: int = -1,
|
requirements.txt
ADDED
@@ -0,0 +1,2 @@
|
|
|
|
|
|
|
1 |
+
torch
|
2 |
+
gradio
|
tokenizers.py
CHANGED
@@ -2,7 +2,6 @@ import time
|
|
2 |
from typing import *
|
3 |
import re
|
4 |
import json
|
5 |
-
import numba
|
6 |
|
7 |
|
8 |
def sample_vocab(tokens: Iterable[str], vocab_size: Optional[int] = None,
|
|
|
2 |
from typing import *
|
3 |
import re
|
4 |
import json
|
|
|
5 |
|
6 |
|
7 |
def sample_vocab(tokens: Iterable[str], vocab_size: Optional[int] = None,
|