flash-attention/hopper/test_attn_kvcache.py

487 lines
19 KiB
Python

import pytest
from einops import rearrange, repeat
import torch
import flash_attn
import flash_attn_interface
import itertools
import math
import time
def construct_local_mask(
seqlen_q,
seqlen_k,
window_size=(-1, -1), # -1 means infinite window size
query_padding_mask=None,
key_padding_mask=None,
device=None,
key_leftpad=None,
):
row_idx = rearrange(torch.arange(seqlen_q, device=device, dtype=torch.long), "s -> s 1")
col_idx = torch.arange(seqlen_k, device=device, dtype=torch.long)
if key_leftpad is not None:
key_leftpad = rearrange(key_leftpad, "b -> b 1 1 1")
col_idx = repeat(col_idx, "s -> b 1 1 s", b=key_leftpad.shape[0])
col_idx = torch.where(col_idx >= key_leftpad, col_idx - key_leftpad, 2**32)
sk = (
seqlen_k
if key_padding_mask is None
else rearrange(key_padding_mask.sum(-1), "b -> b 1 1 1")
)
sq = (
seqlen_q
if query_padding_mask is None
else rearrange(query_padding_mask.sum(-1), "b -> b 1 1 1")
)
if window_size[0] < 0:
return col_idx > row_idx + sk - sq + window_size[1]
else:
sk = torch.full_like(col_idx, seqlen_k) if key_padding_mask is None else sk
return torch.logical_or(
col_idx > torch.minimum(row_idx + sk - sq + window_size[1], sk),
col_idx < row_idx + sk - sq - window_size[0],
)
def attention_ref(
q,
k,
v,
query_padding_mask=None,
key_padding_mask=None,
attn_bias=None,
dropout_p=0.0,
dropout_mask=None,
causal=False,
window_size=(-1, -1), # -1 means infinite window size
softcap=0.0,
upcast=True,
reorder_ops=False,
key_leftpad=None,
):
"""
Arguments:
q: (batch_size, seqlen_q, nheads, head_dim)
k: (batch_size, seqlen_k, nheads_k, head_dim)
v: (batch_size, seqlen_k, nheads_k, head_dim)
query_padding_mask: (batch_size, seqlen_q)
key_padding_mask: (batch_size, seqlen_k)
attn_bias: broadcastable to (batch_size, nheads, seqlen_q, seqlen_k)
dropout_p: float
dropout_mask: (batch_size, nheads, seqlen_q, seqlen_k)
causal: whether to apply causal masking
window_size: (int, int), left and right window size
upcast: whether to cast all inputs to fp32, do all computation in fp32, then cast
output back to fp16/bf16.
reorder_ops: whether to change the order of operations (scaling k instead of scaling q, etc.)
without changing the math. This is to estimate the numerical error from operation
reordering.
Output:
output: (batch_size, seqlen_q, nheads, head_dim)
attention: (batch_size, nheads, seqlen_q, seqlen_k), softmax after dropout
"""
if causal:
window_size = (window_size[0], 0)
dtype_og = q.dtype
if upcast:
q, k, v = q.float(), k.float(), v.float()
seqlen_q, seqlen_k = q.shape[1], k.shape[1]
k = repeat(k, "b s h d -> b s (h g) d", g=q.shape[2] // k.shape[2])
v = repeat(v, "b s h d -> b s (h g) d", g=q.shape[2] // v.shape[2])
d = q.shape[-1]
if not reorder_ops:
scores = torch.einsum("bthd,bshd->bhts", q / math.sqrt(d), k)
else:
scores = torch.einsum("bthd,bshd->bhts", q, k / math.sqrt(d))
if softcap > 0:
scores = scores / softcap
scores = scores.tanh()
scores = scores * softcap
if key_padding_mask is not None:
scores.masked_fill_(rearrange(~key_padding_mask, "b s -> b 1 1 s"), float("-inf"))
if window_size[0] >= 0 or window_size[1] >= 0:
local_mask = construct_local_mask(
seqlen_q,
seqlen_k,
window_size,
query_padding_mask,
key_padding_mask,
q.device,
key_leftpad=key_leftpad,
)
scores.masked_fill_(local_mask, float("-inf"))
if attn_bias is not None:
scores = scores + attn_bias
attention = torch.softmax(scores, dim=-1).to(v.dtype)
# Some rows might be completely masked out so we fill them with zero instead of NaN
if window_size[0] >= 0 or window_size[1] >= 0:
attention = attention.masked_fill(torch.all(local_mask, dim=-1, keepdim=True), 0.0)
# We want to mask here so that the attention matrix doesn't have any NaNs
# Otherwise we'll get NaN in dV
if query_padding_mask is not None:
attention = attention.masked_fill(rearrange(~query_padding_mask, "b s -> b 1 s 1"), 0.0)
dropout_scaling = 1.0 / (1 - dropout_p)
# attention_drop = attention.masked_fill(~dropout_mask, 0.0) * dropout_scaling
# output = torch.einsum('bhts,bshd->bthd', attention_drop , v)
if dropout_mask is not None:
attention_drop = attention.masked_fill(~dropout_mask, 0.0)
else:
attention_drop = attention
output = torch.einsum("bhts,bshd->bthd", attention_drop, v * dropout_scaling)
if query_padding_mask is not None:
output.masked_fill_(rearrange(~query_padding_mask, "b s -> b s 1 1"), 0.0)
return output.to(dtype=dtype_og), attention.to(dtype=dtype_og)
@pytest.mark.parametrize("causal", [True, False])
@pytest.mark.parametrize("num_requests", [1, 4])
@pytest.mark.parametrize("query_seqlen", [1, 8, 120])
@pytest.mark.parametrize("context_seqlen", [1024, 3131, 4224])
@pytest.mark.parametrize("headdim", [64, 128, 256])
@pytest.mark.parametrize("gqa_parallel", [False, True])
@pytest.mark.parametrize(
"nheads_kv, gqa_ratio",
[
(1, 1),
(2, 5),
(3, 3),
(1, 32),
(5, 7),
(8, 1),
(1, 16),
(12, 4),
(8, 2),
],
)
def test_flash_attn_kvcache_nosplit(nheads_kv, gqa_ratio, num_requests, query_seqlen, context_seqlen, headdim, causal, gqa_parallel):
device = "cuda"
num_caches = num_requests
cache_seqlen = context_seqlen
nheads_q = nheads_kv * gqa_ratio
k_cache = torch.randn(
(num_caches, cache_seqlen, nheads_kv, headdim), device="cuda", dtype=torch.bfloat16
)
v_cache = torch.randn(
(num_caches, cache_seqlen, nheads_kv, headdim), device="cuda", dtype=torch.bfloat16
)
q = torch.randn((num_requests, query_seqlen, nheads_q, headdim), device="cuda", dtype=torch.bfloat16)
# cache_idxs = torch.randperm(num_caches, dtype=torch.int32, device="cuda")[:num_requests]
cache_seqlens = torch.tensor([context_seqlen] * num_requests, dtype=torch.int32, device="cuda")
torch.cuda.synchronize()
out_ref, _ = attention_ref(
q,
k_cache,
v_cache,
causal=causal,
)
out_fa3, lse_fa3 = flash_attn_interface.flash_attn_with_kvcache(
q=q,
k_cache=k_cache,
v_cache=v_cache,
cache_seqlens=cache_seqlens,
# cache_batch_idx=cache_idxs,
causal=causal,
num_splits=1,
return_softmax_lse=True,
gqa_parallel=gqa_parallel
)
torch.cuda.synchronize()
assert ((out_ref - out_fa3).abs().max().item() <= 4e-3)
assert ((out_ref - out_fa3).abs().mean().item() <= 2e-4)
@pytest.mark.parametrize("causal", [True, False])
@pytest.mark.parametrize("num_requests", [1, 3])
@pytest.mark.parametrize("query_seqlen", [1, 8, 120])
@pytest.mark.parametrize("context_seqlen", [1600, 4000, 5555])
@pytest.mark.parametrize("headdim", [64, 128, 256])
@pytest.mark.parametrize("gqa_parallel", [True, False])
@pytest.mark.parametrize(
"nheads_kv, gqa_ratio",
[
(1, 1),
(2, 5),
(3, 3),
(1, 32),
(5, 7),
(8, 1),
(1, 16),
(12, 4),
(8, 2),
],
)
def test_flash_attn_kvcache_nosplit_fp8(nheads_kv, gqa_ratio, num_requests, query_seqlen, context_seqlen, headdim, causal, gqa_parallel):
device = "cuda"
num_caches = num_requests
cache_seqlen = context_seqlen
nheads_q = nheads_kv * gqa_ratio
k_cache = torch.randn(
(num_caches, cache_seqlen, nheads_kv, headdim), device="cuda", dtype=torch.bfloat16
)
v_cache = torch.randn(
(num_caches, cache_seqlen, nheads_kv, headdim), device="cuda", dtype=torch.bfloat16
)
q = torch.randn((num_requests, query_seqlen, nheads_q, headdim), device="cuda", dtype=torch.bfloat16)
q = q.to(torch.float8_e4m3fn)
k_cache = k_cache.to(torch.float8_e4m3fn)
v_cache = v_cache.to(torch.float8_e4m3fn)
# cache_idxs = torch.randperm(num_caches, dtype=torch.int32, device="cuda")[:num_requests]
cache_seqlens = torch.tensor([context_seqlen] * num_requests, dtype=torch.int32, device="cuda")
torch.cuda.synchronize()
out_ref, _ = attention_ref(
q,
k_cache,
v_cache,
causal=causal,
)
descale_q = torch.tensor([1.0], dtype=torch.float32, device='cuda')
descale_k = torch.tensor([1.0], dtype=torch.float32, device='cuda')
descale_v = torch.tensor([1.0], dtype=torch.float32, device='cuda')
out_fa3, lse_fa3 = flash_attn_interface.flash_attn_with_kvcache(
q=q,
k_cache=k_cache,
v_cache=v_cache,
cache_seqlens=cache_seqlens,
# cache_batch_idx=cache_idxs,
causal=causal,
num_splits=1,
return_softmax_lse=True,
gqa_parallel=gqa_parallel,
descale_q=descale_q, descale_k=descale_k, descale_v=descale_v
)
torch.cuda.synchronize()
assert ((out_ref - out_fa3).abs().max().item() <= 4e-2)
assert ((out_ref - out_fa3).abs().mean().item() <= 2e-3)
@pytest.mark.parametrize("dtype", [torch.bfloat16])
@pytest.mark.parametrize("use_heuristic_only", [True])
# @pytest.mark.parametrize("use_heuristic_only", [False])
@pytest.mark.parametrize("causal", [True, False])
# @pytest.mark.parametrize("num_requests", [1, 4, 16])
@pytest.mark.parametrize("num_requests", [1, 3])
# @pytest.mark.parametrize("query_seqlen", [1, 16, 32, 128])
@pytest.mark.parametrize("query_seqlen", [1, 8, 25])
# @pytest.mark.parametrize("context_seqlen", [4096, 16384, 65536])
@pytest.mark.parametrize("context_seqlen", [1600, 4000, 5555])
@pytest.mark.parametrize("headdim", [64, 128, 256])
@pytest.mark.parametrize("cache_seqlen_rand", [True, False])
@pytest.mark.parametrize("gqa_parallel", [True, False])
@pytest.mark.parametrize(
"nheads_kv, gqa_ratio",
[
(1, 1),
(4, 1),
(2, 2),
(3, 3),
(4, 4),
(2, 5),
(3, 9),
(1, 16),
(1, 32),
],
)
def test_flash_attn_kvcache_output(nheads_kv, gqa_ratio, num_requests, query_seqlen, context_seqlen, headdim, causal, use_heuristic_only, cache_seqlen_rand, gqa_parallel, dtype):
device = "cuda"
num_caches = 16
if context_seqlen <= 65536:
cache_seqlen = 65536
else:
cache_seqlen = context_seqlen
nheads_q = nheads_kv * gqa_ratio
if use_heuristic_only:
max_splits = 1
else:
max_splits = 128
k_cache = torch.randn(
(num_caches, cache_seqlen, nheads_kv, headdim), device="cuda", dtype=torch.bfloat16
)
v_cache = torch.randn(
(num_caches, cache_seqlen, nheads_kv, headdim), device="cuda", dtype=torch.bfloat16
)
q = torch.randn((num_requests, query_seqlen, nheads_q, headdim), device="cuda", dtype=torch.bfloat16)
q = q.to(dtype)
k_cache = k_cache.to(dtype)
v_cache = v_cache.to(dtype)
cache_idxs = torch.randperm(num_caches, dtype=torch.int32, device="cuda")[:num_requests]
cache_seqlens = torch.randint(1, context_seqlen-1, (num_requests,), dtype=torch.int32).to(device) if cache_seqlen_rand else torch.tensor([context_seqlen] * num_requests, dtype=torch.int32, device="cuda")
torch.cuda.synchronize()
out_ref, lse_ref = flash_attn_interface.flash_attn_with_kvcache(
q=q,
k_cache=k_cache,
v_cache=v_cache,
cache_seqlens=cache_seqlens,
cache_batch_idx=cache_idxs,
causal=causal,
num_splits=1,
return_softmax_lse=True,
gqa_parallel=False
)
# i=0 case is with num splits heuristic
for i in range(0, max_splits+1):
out_fa3, lse_fa3 = flash_attn_interface.flash_attn_with_kvcache(
q=q,
k_cache=k_cache,
v_cache=v_cache,
cache_seqlens=cache_seqlens,
cache_batch_idx=cache_idxs,
causal=causal,
num_splits=i,
return_softmax_lse=True,
gqa_parallel=gqa_parallel,
max_seqlen_k_hint=context_seqlen
)
torch.cuda.synchronize()
print ('output-ref', i, out_ref)
print ('output-fa3',i, out_fa3)
print ('output-max-diff', i, context_seqlen, (out_ref - out_fa3).abs().max().item())
print ('output-mean-diff',i, context_seqlen, (out_ref - out_fa3).abs().mean().item())
print ('lse-max-diff',i, context_seqlen, (lse_ref - lse_fa3).abs().max().item())
print ('lse-mean-diff',i, context_seqlen, (lse_ref - lse_fa3).abs().mean().item())
if cache_seqlen_rand:
assert ((out_ref - out_fa3).abs().max().item() <= 1e-2)
assert ((out_ref - out_fa3).abs().mean().item() <= 1e-3)
else:
assert ((out_ref - out_fa3).abs().max().item() <= 2e-3)
assert ((out_ref - out_fa3).abs().mean().item() <= 1e-4)
lse_max_ref = lse_ref.abs().max().item()
lse_mean_ref = lse_ref.abs().mean().item()
lse_max_fa3 = lse_fa3.abs().max().item()
lse_mean_fa3 = lse_fa3.abs().mean().item()
lse_max_diff = (lse_ref - lse_fa3).abs().max().item()
lse_mean_diff = (lse_ref - lse_fa3).abs().mean().item()
assert ((lse_max_ref == math.inf and lse_max_fa3 == math.inf) or lse_max_diff <= 1e-3)
assert ((lse_mean_ref == math.inf and lse_mean_fa3 == math.inf) or lse_mean_diff <= 1e-4)
@pytest.mark.parametrize("dtype", [torch.float8_e4m3fn])
@pytest.mark.parametrize("use_heuristic_only", [True])
# @pytest.mark.parametrize("use_heuristic_only", [False])
@pytest.mark.parametrize("causal", [True, False])
# @pytest.mark.parametrize("num_requests", [1, 4, 16])
@pytest.mark.parametrize("num_requests", [1, 3])
# @pytest.mark.parametrize("query_seqlen", [1, 16, 32, 128])
@pytest.mark.parametrize("query_seqlen", [1, 8, 25])
# @pytest.mark.parametrize("context_seqlen", [4096, 16384, 65536])
@pytest.mark.parametrize("context_seqlen", [1600, 4000, 5555])
@pytest.mark.parametrize("headdim", [64, 128, 256])
@pytest.mark.parametrize("cache_seqlen_rand", [True, False])
@pytest.mark.parametrize("gqa_parallel", [True, False])
@pytest.mark.parametrize(
"nheads_kv, gqa_ratio",
[
(1, 1),
(4, 1),
(2, 2),
(3, 3),
(4, 4),
(2, 5),
(3, 9),
(1, 16),
(1, 32),
],
)
def test_flash_attn_kvcache_output_fp8(nheads_kv, gqa_ratio, num_requests, query_seqlen, context_seqlen, headdim, causal, use_heuristic_only, cache_seqlen_rand, gqa_parallel, dtype):
device = "cuda"
num_caches = 16
if context_seqlen <= 65536:
cache_seqlen = 65536
else:
cache_seqlen = context_seqlen
nheads_q = nheads_kv * gqa_ratio
if use_heuristic_only:
max_splits = 1
else:
max_splits = 128
k_cache = torch.randn(
(num_caches, cache_seqlen, nheads_kv, headdim), device="cuda", dtype=torch.bfloat16
)
v_cache = torch.randn(
(num_caches, cache_seqlen, nheads_kv, headdim), device="cuda", dtype=torch.bfloat16
)
q = torch.randn((num_requests, query_seqlen, nheads_q, headdim), device="cuda", dtype=torch.bfloat16)
q = q.to(dtype)
k_cache = k_cache.to(dtype)
v_cache = v_cache.to(dtype)
cache_idxs = torch.randperm(num_caches, dtype=torch.int32, device="cuda")[:num_requests]
cache_seqlens = torch.randint(1, context_seqlen-1, (num_requests,), dtype=torch.int32).to(device) if cache_seqlen_rand else torch.tensor([context_seqlen] * num_requests, dtype=torch.int32, device="cuda")
torch.cuda.synchronize()
descale_q = torch.tensor([1.0], dtype=torch.float32, device='cuda')
descale_k = torch.tensor([1.0], dtype=torch.float32, device='cuda')
descale_v = torch.tensor([1.0], dtype=torch.float32, device='cuda')
out_ref, lse_ref = flash_attn_interface.flash_attn_with_kvcache(
q=q,
k_cache=k_cache,
v_cache=v_cache,
cache_seqlens=cache_seqlens,
cache_batch_idx=cache_idxs,
causal=causal,
num_splits=1,
return_softmax_lse=True,
gqa_parallel=False,
descale_q=descale_q, descale_k=descale_k, descale_v=descale_v
)
# i=0 case is with num splits heuristic
for i in range(0, max_splits+1):
out_fa3, lse_fa3 = flash_attn_interface.flash_attn_with_kvcache(
q=q,
k_cache=k_cache,
v_cache=v_cache,
cache_seqlens=cache_seqlens,
cache_batch_idx=cache_idxs,
causal=causal,
num_splits=i,
return_softmax_lse=True,
gqa_parallel=gqa_parallel,
max_seqlen_k_hint=context_seqlen,
descale_q=descale_q, descale_k=descale_k, descale_v=descale_v
)
torch.cuda.synchronize()
print ('output-ref', i, out_ref)
print ('output-fa3',i, out_fa3)
print ('output-max-diff', i, context_seqlen, (out_ref - out_fa3).abs().max().item())
print ('output-mean-diff',i, context_seqlen, (out_ref - out_fa3).abs().mean().item())
print ('lse-max-diff',i, context_seqlen, (lse_ref - lse_fa3).abs().max().item())
print ('lse-mean-diff',i, context_seqlen, (lse_ref - lse_fa3).abs().mean().item())
if cache_seqlen_rand:
assert ((out_ref - out_fa3).abs().max().item() <= 1e-1)
assert ((out_ref - out_fa3).abs().mean().item() <= 1e-2)
else:
assert ((out_ref - out_fa3).abs().max().item() <= 2e-2)
assert ((out_ref - out_fa3).abs().mean().item() <= 2e-3)
lse_max_ref = lse_ref.abs().max().item()
lse_mean_ref = lse_ref.abs().mean().item()
lse_max_fa3 = lse_fa3.abs().max().item()
lse_mean_fa3 = lse_fa3.abs().mean().item()
lse_max_diff = (lse_ref - lse_fa3).abs().max().item()
lse_mean_diff = (lse_ref - lse_fa3).abs().mean().item()
assert ((lse_max_ref == math.inf and lse_max_fa3 == math.inf) or lse_max_diff <= 1e-3)
assert ((lse_mean_ref == math.inf and lse_mean_fa3 == math.inf) or lse_mean_diff <= 1e-4)
if __name__ == "__main__":
main()