kvcache-ai-ktransformers/ktransformers/operators/flashinfer_wrapper.py
2025-04-01 07:30:23 +00:00

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Python

'''
Description : flashinfer MLA wrapper
Author : Boxin Zhang
Version : 0.2.3
'''
import torch
import os
from ktransformers.operators.triton_attention import decode_attention_fwd_grouped
flashinfer_enabled = False
try:
import flashinfer
flashinfer_enabled = True
print("found flashinfer")
except ImportError:
print("flashinfer not found, use triton for linux")
import math
def attention_ref_torch(
batch_size,
q: torch.Tensor,
k: torch.Tensor,
v: torch.Tensor,
causal: bool,
sm_scale: float,
) -> torch.Tensor:
qo_len = q.shape[0] // batch_size
kv_len = k.shape[0] // batch_size
num_qo_heads = q.shape[1]
head_dim_qk = q.shape[2]
head_dim_vo = v.shape[2]
logits = (
torch.einsum(
"bmhd,bnhd->bhmn",
q.view(batch_size, qo_len, num_qo_heads, head_dim_qk).float(),
k.view(batch_size, kv_len, num_qo_heads, head_dim_qk).float(),
)
* sm_scale
)
#print("attn weights", logits)
if causal:
mask = (
torch.arange(kv_len - qo_len, kv_len).unsqueeze(1)
>= torch.arange(0, kv_len).unsqueeze(0)
).to(q.device)
else:
mask = torch.ones(qo_len, kv_len).to(q.device)
logits = logits.masked_fill(mask.unsqueeze(0).unsqueeze(0) == 0, float("-inf"))
lse_ref = torch.logsumexp(logits, -1).transpose(-1, -2)
p = torch.softmax(logits, dim=-1)
o_ref = (
torch.einsum(
"bhmn,bnhd->bmhd",
p,
v.view(batch_size, kv_len, num_qo_heads, head_dim_vo).float(),
)
.contiguous()
.view(batch_size * qo_len, num_qo_heads, head_dim_vo)
.to(q)
)
return o_ref, lse_ref * math.log2(math.e)
class MLAWrapper():
def __init__(self,
max_batch_size,
max_pages,
use_cuda_graph = True,
device = "cuda",
):
self.float_workspace_buffer = torch.empty(128*1024*1024, dtype=torch.int8, device=device)
self.max_batch_size = max_batch_size
self.max_pages = max_pages
if use_cuda_graph:
if self.max_batch_size == 1:
self.qo_indptr_buf = torch.arange(0, max_batch_size+1, dtype=torch.int32, device=device)
self.kv_indptr_buf = torch.tensor([0, max_pages], dtype=torch.int32, device=device)
self.kv_indices_buf = torch.arange(0, max_pages, dtype=torch.int32, device=device)
else:
self.qo_indptr_buf = torch.empty(max_batch_size+1, dtype=torch.int32, device=device)
self.kv_indptr_buf = torch.empty(max_batch_size+1, dtype=torch.int32, device=device)
self.kv_indices_buf = torch.empty(max_pages, dtype=torch.int32, device=device)
self.batch_size_tensor_buf = torch.tensor([self.max_batch_size], dtype=torch.int32, device=device)
self.kv_len_arr_buf = torch.empty(max_batch_size, dtype=torch.int32, device=device)
else:
self.qo_indptr_buf = None
self.kv_indptr_buf = None
self.kv_indices_buf = None
self.kv_len_arr_buf = None
self.wrapper = flashinfer.mla.BatchMLAPagedAttentionWrapper(
self.float_workspace_buffer,
use_cuda_graph=use_cuda_graph,
qo_indptr=self.qo_indptr_buf,
kv_indptr=self.kv_indptr_buf,
kv_indices=self.kv_indices_buf,
kv_len_arr=self.kv_len_arr_buf,
bsz_tensor=self.batch_size_tensor_buf
)
self.need_plan = True
def plan(self,
qo_indptr,
kv_indptr,
kv_indices,
kv_len_arr,
bsz_tensor,
num_heads,
head_dim_ckv,
head_dim_kpe,
page_size,
sm_scale,
q_data_type,
kv_data_type,
):
if qo_indptr is None:
assert self.max_batch_size == 1
qo_indptr = self.qo_indptr_buf
if kv_indptr is None:
assert self.max_batch_size == 1
kv_indptr = self.kv_indptr_buf
if kv_indices is None:
assert self.max_batch_size == 1
kv_indices = self.kv_indices_buf
if bsz_tensor is None:
assert self.max_batch_size == 1
bsz_tensor = self.batch_size_tensor_buf
self.wrapper.plan(
qo_indptr,
kv_indptr,
kv_indices,
kv_len_arr,
num_heads,
head_dim_ckv,
head_dim_kpe,
page_size,
True, # causal
sm_scale,
q_data_type,
kv_data_type,
bsz_tensor
)
def run(self, q_nope, q_pe, ckv, k_pe, return_lse = False):
return self.wrapper.run(q_nope, q_pe, ckv, k_pe, return_lse = return_lse)
class MLAWrapperSingleton():
wrappers:dict = {}
@classmethod
def get_instance(cls, device, *args, **kwargs)->MLAWrapper:
if device not in cls.wrappers:
cls.make_instance(device, *args, **kwargs)
return cls.wrappers[device]
@classmethod
def make_instance(cls, device, *args, **kwargs):
cls.wrappers[device] = MLAWrapper(*args, **kwargs, device=device)
@classmethod
def plan_all(cls, qo_indptr,
kv_indptr,
kv_indices,
kv_len_arr,
bsz_tensor,
num_heads,
head_dim_ckv,
head_dim_kpe,
page_size,
sm_scale,
q_data_type,
kv_data_type,):
for device, wrapper in cls.wrappers.items():
kv_len_arr_cur_device = kv_len_arr.to(device)
wrapper.plan(qo_indptr,
kv_indptr,
kv_indices,
kv_len_arr_cur_device,
bsz_tensor,
num_heads,
head_dim_ckv,
head_dim_kpe,
page_size,
sm_scale,
q_data_type,
kv_data_type,)
wrapper.need_plan = False
@classmethod
def need_plan_all(cls):
for device, wrapper in cls.wrappers.items():
wrapper.need_plan = True
@classmethod
def reset_buffer(cls):
for device, wrapper in cls.wrappers.items():
wrapper.qo_indptr_buf[1] = 1 # assert max_batch_size=1 here.
@classmethod
def update_buffer(cls, max_pages):
for device, wrapper in cls.wrappers.items():
wrapper.kv_indptr_buf[1] = max_pages # assert max_batch_size=1 here.
wrapper.kv_indices_buf = torch.arange(0, max_pages, dtype=torch.int32, device=device)
wrapper.wrapper._kv_indices_buf = wrapper.kv_indices_buf
def checksame():
flashinfer_folder = "./flashinfer_output"
flashinfer_folder = "./kv_cache_flashinfer"
triton_folder = "./triton_output"
triton_folder = "./kv_cache_triton"
max_layer_id = 1
max_forward_id = 2
for forward_id in range(0, 19):
print("forward_id", forward_id)
for layer_id in range(max_layer_id):
print(layer_id)
#file_name = f"layer_{layer_id}_forward_{forward_id}_attn_output.pt"
#file_name = f"layer_{layer_id}_forward_{forward_id}_q_pe.pt"
file_name = f"layer_{layer_id}.pt"
flashinfer_path = os.path.join(flashinfer_folder, file_name)
triton_path = os.path.join(triton_folder, file_name)
if not os.path.exists(triton_path):
print(f"{file_name} not exist in {triton_folder}")
continue
if not os.path.exists(flashinfer_path):
print(f"{file_name} not exist in {flashinfer_folder}")
continue
flashinfer_tensor = torch.load(flashinfer_path)[1:2, :62]#
triton_tensor = torch.load(triton_path)[1:2, :62]#.squeeze(1)#
try:
torch.testing.assert_close(flashinfer_tensor, triton_tensor, rtol=1e-9, atol=1e-9)
except AssertionError as e:
print(e)
if __name__ == "__main__":
#checksame()
#exit(0)
max_batch_size = 2
max_batch_tokens = 256
max_pages = 128
page_size = 64
num_heads = 128
# warm-up
kv_len = 4023
q_len = 1
q_nope_buf = torch.randn((max_batch_tokens, num_heads, 512), dtype=torch.bfloat16, device="cuda")
q_pe_buf = torch.randn((max_batch_tokens, num_heads, 64), dtype=torch.bfloat16, device="cuda")
kv_buf = torch.randn((max_pages, page_size, 576), dtype=torch.bfloat16, device="cuda")
ckv, k_pe = torch.split(kv_buf, [512, 64], dim=-1)
wrapper = MLAWrapperSingleton.get_instance(
"cuda",
max_batch_size,
max_pages,
)
used_pages = (kv_len + page_size - 1)// page_size
kv_len_arr = torch.tensor([kv_len], dtype=torch.int32, device="cuda")
qo_indptr = torch.tensor([0, q_len], dtype=torch.int32, device="cuda")
kv_indptr = torch.tensor([0, used_pages], dtype=torch.int32, device="cuda")
kv_indices = torch.empty(max_pages, dtype=torch.int32, device="cuda")
kv_indices[:used_pages] = torch.arange(0, used_pages, dtype=torch.int32, device="cuda")
bsz_tensor = torch.tensor([1], dtype=torch.int32, device="cuda")
wrapper.plan(
qo_indptr,
kv_indptr,
kv_indices,
kv_len_arr,
bsz_tensor,
128,
512,
64,
page_size,
192 ** (-0.5),
torch.bfloat16,
torch.bfloat16,
)
attn_output = wrapper.run(q_nope_buf[:q_len], q_pe_buf[:q_len], ckv, k_pe)
print(attn_output.shape)
graph = torch.cuda.CUDAGraph()
with torch.cuda.graph(graph):
attn_output = wrapper.run(q_nope_buf, q_pe_buf, ckv, k_pe)
graph.replay()
q = torch.cat([q_nope_buf, q_pe_buf], dim=-1)
k = (
torch.cat([ckv, k_pe], dim=-1)
.view(-1, 1, 512 + 64)
.repeat_interleave(num_heads, dim=1)
)
v = ckv.view(-1, 1, 512).repeat_interleave(num_heads, dim=1)
attn_ref, lse_ref = attention_ref_torch(
1,
q[:q_len],
k[:kv_len],
v[:kv_len],
True,
192 ** (-0.5)
)
torch.testing.assert_close(attn_output[:q_len], attn_ref, rtol=5e-3, atol=5e-3)
# warm-up finished
kv_len = 512
q_len = 128
pages = max_pages
used_pages = (kv_len + page_size - 1)// page_size
q_nope = torch.randn((q_len*2, num_heads, 512), dtype=torch.bfloat16, device="cuda")
q_nope[q_len:] = q_nope[:q_len]
q_pe = torch.randn((q_len*2, num_heads, 64), dtype=torch.bfloat16, device="cuda")
q_pe[q_len:] = q_pe[:q_len]
kv_cache = torch.randn((max_pages, page_size, 576), dtype=torch.bfloat16, device="cuda")
kv_cache[used_pages:2*used_pages] = kv_cache[:used_pages]
ckv, k_pe = torch.split(kv_cache, [512, 64], dim=-1)
kv_len_arr = torch.tensor([kv_len, kv_len], dtype=torch.int32, device="cuda")
qo_indptr = torch.tensor([0, q_len, q_len*2], dtype=torch.int32, device="cuda")
kv_indptr = torch.tensor([0, used_pages, used_pages*2], dtype=torch.int32, device="cuda")
kv_indices = torch.empty(max_pages, dtype=torch.int32, device="cuda")
kv_indices[:2*used_pages] = torch.arange(0, 2*used_pages, dtype=torch.int32, device="cuda")
bsz_tensor = torch.tensor([2], dtype=torch.int32, device="cuda")
wrapper.plan(
qo_indptr,
kv_indptr,
kv_indices,
kv_len_arr,
bsz_tensor,
128,
512,
64,
page_size,
192 ** (-0.5),
torch.bfloat16,
torch.bfloat16,
)
q_nope_buf.copy_(q_nope)
q_pe_buf.copy_(q_pe)
kv_buf[:pages].copy_(kv_cache)
torch.cuda.synchronize()
graph.replay()
torch.cuda.synchronize()
# ref_torch
q = torch.cat([q_nope, q_pe], dim=-1)
k = (
torch.cat([ckv, k_pe], dim=-1)
.view(-1, 1, 512 + 64)
.repeat_interleave(num_heads, dim=1)
)
v = ckv.view(-1, 1, 512).repeat_interleave(num_heads, dim=1)
attn_ref, lse_ref = attention_ref_torch(
max_batch_size,
q,
k[:2*kv_len],
v[:2*kv_len],
True,
192 ** (-0.5)
)
torch.testing.assert_close(attn_ref[:q_len], attn_ref[q_len:q_len*2], rtol=1e-9, atol=1e-9)
torch.testing.assert_close(attn_output[:q_len], attn_output[q_len:q_len*2], rtol=1e-9, atol=1e-9)
torch.testing.assert_close(attn_output[:q_len], attn_ref[:q_len], rtol=5e-3, atol=5e-3)
torch.testing.assert_close(attn_output[q_len:q_len*2], attn_ref[q_len:q_len*2], rtol=5e-3, atol=5e-3)
#torch.testing.assert_close(attn_output[:q_len], attn_output[q_len:q_len*2], rtol=1e-9, atol=1e-9)
#torch.testing.assert_close(attn_output, attn_ref, rtol=5e-3, atol=5e-3)
exit(0)
for forward_id in range(0, 1):
print("forward_id", forward_id)
for layer_id in range(1):
print(layer_id)
flashinfer_folder = "./kv_cache_flashinfer"
forward_id = 17
layer_id = 0
file_name = f"layer_{layer_id}.pt"
kv_cache_path = os.path.join(flashinfer_folder, file_name)
flashinfer_folder = "./flashinfer_output"
q_len = 1
kv_len = 126
file_name = f"layer_{layer_id}_forward_{forward_id}_q_nope.pt"
q_nope = torch.load(os.path.join(flashinfer_folder, file_name)).view(q_len,128,512).to(device="cuda")
file_name = f"layer_{layer_id}_forward_{forward_id}_q_pe.pt"
q_pe = torch.load(os.path.join(flashinfer_folder, file_name)).view(q_len,128,64).to(device="cuda")
q = torch.cat([q_nope, q_pe], dim=-1)
kv_cache = torch.load(kv_cache_path).to(device="cuda")
pages, page_size, _, head_dim = kv_cache.shape
kv_cache = kv_cache.view(pages, page_size, head_dim)
ckv, k_pe = torch.split(kv_cache, [512, 64], dim=-1)
kv_len_arr = torch.tensor([kv_len], dtype=torch.int32, device="cuda")
qo_indptr = torch.tensor([0, q_len], dtype=torch.int32, device="cuda")
wrapper.plan(
None,
None,
None,
kv_len_arr,
128,
512,
64,
page_size,
192 ** (-0.5),
torch.bfloat16,
torch.bfloat16,
)
q_nope_buf.copy_(q_nope)
q_pe_buf.copy_(q_pe)
kv_buf[:pages].copy_(kv_cache)
torch.cuda.synchronize()
graph.replay()
torch.cuda.synchronize()
# ref_torch
k = (
torch.cat([ckv, k_pe], dim=-1)
.view(-1, 1, 512 + 64)
.repeat_interleave(num_heads, dim=1)
)
v = ckv.view(-1, 1, 512).repeat_interleave(num_heads, dim=1)
attn_ref, lse_ref = attention_ref_torch(
max_batch_size,
q,
k[:kv_len],
v[:kv_len],
False,
192 ** (-0.5)
)
torch.testing.assert_close(attn_output, attn_ref, rtol=1e-3, atol=1e-3)
# ref_triton
attn_logits = torch.empty(
(
max_batch_size,
num_heads,
4, #num_kv_splits # follow vLLM, fix it TODO
512 + 1,
),
dtype=torch.float32,
device = "cuda"
)
triton_ref = torch.zeros_like(q_nope)
page_table = torch.arange(max_pages, dtype=torch.int32, device="cuda")
ckv_with_pe = torch.cat([ckv, k_pe], dim=-1).contiguous().view(pages, page_size, 1, 576)
ckv = ckv.view(pages, page_size, 1, 512)
decode_attention_fwd_grouped(q, ckv_with_pe, ckv, triton_ref,
page_table,
kv_len_arr, attn_logits,
4, #num_kv_splits # follow vLLM, fix it TODO
192 ** (-0.5),
page_size)
torch.testing.assert_close(attn_output, triton_ref, rtol=1e-3, atol=1e-3)
#file_name = f"./flashinfer_output/layer_{layer_id}_forward_{forward_id}_attn_output.pt"
#ktrans_output = torch.load(file_name)
#torch.testing.assert_close(attn_output, ktrans_output.squeeze(1), rtol=1e-3, atol=1e-3)
print("test past")