[PYTHON][OPS] Added block-sparse softmax

This commit is contained in:
Philippe Tillet
2021-01-30 19:58:42 -05:00
parent f81da73b6a
commit 7ba242fcce
4 changed files with 373 additions and 2 deletions

View File

@@ -23,7 +23,7 @@ def mask_tensor(x, mask, block, value = 0):
for block in [16, 32, 64]
]
)
def test_op(MODE, TRANS_A, TRANS_B, BLOCK, DTYPE = torch.float16, Z = 3, H = 2, M = 128, N = 256, K = 384):
def test_matmul(MODE, TRANS_A, TRANS_B, BLOCK, DTYPE = torch.float16, Z = 3, H = 2, M = 128, N = 256, K = 384):
# set seed
torch.random.manual_seed(0)
# create inputs
@@ -48,3 +48,42 @@ def test_op(MODE, TRANS_A, TRANS_B, BLOCK, DTYPE = torch.float16, Z = 3, H = 2,
rtol, atol = {torch.float32: (1e-4, 1e-5),
torch.float16: (1e-2, 1e-3)}[DTYPE]
assert torch.allclose(rc, tc, rtol=rtol, atol=atol)
@pytest.mark.parametrize("BLOCK, WIDTH",
[
(block, width) for block in [16]\
for width in [256, 576]
]
)
def test_softmax(BLOCK, WIDTH, DTYPE = torch.float16):
# set seed
torch.random.manual_seed(0)
Z, H, M, N = 2, 4, WIDTH, WIDTH
scale = 0.4
# create inputs
layout = torch.randint(2, (H, M//BLOCK, N//BLOCK))
x = torch.randn((Z, H, M, N), dtype=DTYPE, requires_grad=True, device='cuda')
at_mask = torch.randint(low=0, high=2, size=(N, N), \
dtype=torch.bool, requires_grad=False, device='cuda')
kp_mask = torch.randint(low=0, high=2, size=(Z, N), \
dtype=DTYPE, requires_grad=False, device='cuda')
kp_mask[kp_mask==1.] = float('-inf')
# triton result
op = tt.ops.blocksparse.softmax(layout, BLOCK)
tx = sparsify_tensor(x, layout, BLOCK)
ty = op(tx, scale=scale, key_padding_mask=kp_mask, key_padding_mask_mode='add', attn_mask=at_mask.to(DTYPE), attn_mask_mode='mul')
# torch result
rx = mask_tensor(x, layout, BLOCK, value=float('-inf'))
if at_mask is not None:
# broadcast at_mask to the same shape as rx
M = at_mask[None, None, :, :] + torch.zeros_like(rx)
rx[M == 0] = float('-inf')
if kp_mask is not None:
rx += kp_mask[:, None, None, :]
ry = torch.softmax(rx*scale, -1)
ry = sparsify_tensor(ry, layout, BLOCK)
# compare
rtol, atol = {torch.float32: (1e-4, 1e-5),
torch.float16: (1e-2, 1e-3)}[DTYPE]
assert torch.allclose(ry , ty, rtol=rtol, atol=atol)

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@@ -1 +1,2 @@
from .matmul import matmul
from .matmul import matmul
from .softmax import softmax

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@@ -0,0 +1,154 @@
__global__ void forward(TYPE *X __readonly __noalias __aligned(16),
float scale,
int *LUT __readonly __noalias __aligned(16),
TYPE *RPE __readonly __noalias __aligned(16),
TYPE *KP_M __readonly __noalias __aligned(16),
TYPE *ATTN_M __readonly __noalias __aligned(16),
int sizemax,
long stride_zx __multipleof(BLOCK),
long stride_zrpe __multipleof(BLOCK),
int stride_hrpe __multipleof(BLOCK),
int stride_srpe __multipleof(BLOCK),
int stride_zkpm __multipleof(BLOCK),
int stride_zattnm __multipleof(BLOCK)){
int pidhm = get_program_id(0);
int pidz = get_program_id(1);
// create index ranges
int rxm = pidhm % BLOCK;
int rbm = pidhm / BLOCK;
int rxn[TN] = (0 ... TN) % BLOCK;
int rbn[TN] = (0 ... TN) / BLOCK;
// extract information from look-up table
int* header = LUT + rbm * 2;
int size = *(header + 0);
int offset = *(header + 1);
bool check[TN] = rbn < size;
int rbmn[TN] = check ? rbn : size - 1;
// block id and column id
long blockid [TN] = *(LUT + offset + rbmn*4 + 0);
long columnid[TN] = *(LUT + offset + rbmn*4 + 1);
long rowid [TN] = *(LUT + offset + rbmn*4 + 2);
long headid [TN] = *(LUT + offset + rbmn*4 + 3);
// pointers to X
TYPE* px[TN] = X + pidz * stride_zx
+ blockid * BLOCK * BLOCK
+ rxm * BLOCK
+ rxn;
#ifdef APPLY_RPE
// pointers to relative position embedding
TYPE* prpe[TN] = RPE + pidz * stride_zrpe
+ headid * stride_hrpe
+ columnid * BLOCK
+ rowid * BLOCK * stride_srpe
+ rxm * stride_srpe
+ rxn;
#endif
#ifdef APPLY_KP_MASK
// pointers to key padding mask
TYPE* pkp_m[TN] = KP_M + pidz * stride_zkpm
+ columnid * BLOCK
+ rxn;
#endif
#ifdef APPLY_ATTN_MASK
// pointers to attention mask
TYPE* pattn_m[TN] = ATTN_M + columnid * BLOCK
+ rowid * BLOCK * stride_zattnm
+ rxm * stride_zattnm
+ rxn;
#endif
// load input
TYPE x[TN] = check ? *px : -INFINITY;
#ifdef APPLY_RPE
// load relative position embedding
TYPE rpe[TN] = check ? *prpe : 0;
#endif
#ifdef APPLY_KP_MASK
// load key-padding mask
TYPE kp_m[TN] = check ? *pkp_m : -INFINITY;
#endif
#ifdef APPLY_ATTN_MASK
// load attention mask
TYPE attn_m[TN] = check ? *pattn_m : -INFINITY;
#endif
// compute softmax in float
#ifdef APPLY_RPE
float Frpe[TN] = rpe;
#endif
#ifdef APPLY_KP_MASK
float Fkp_m[TN] = kp_m;
#endif
#ifdef APPLY_ATTN_MASK
float Fattn_m[TN] = attn_m;
#endif
#ifdef KP_MASK_MUL
Fkp_m = (Fkp_m == 0) ? (float[TN])-INFINITY : 0;
#endif
#ifdef ATTN_MASK_MUL
Fattn_m = (Fattn_m == 0) ? (float[TN])-INFINITY : 0;
#endif
float Fx[TN] = x;
#ifdef APPLY_SCALE
Fx = Fx * scale; // apply scale
#endif
#ifdef APPLY_RPE
Fx = Fx + Frpe; // apply relative position embedding
#endif
#ifdef APPLY_KP_MASK
Fx = Fx + Fkp_m; // apply key padding mask
#endif
#ifdef APPLY_ATTN_MASK
Fx = Fx + Fattn_m; // apply attention mask
#endif
float Fxmax = Fx[max];
float Fy[TN] = exp(Fx - Fxmax);
float Fysum = (check ? Fy : 0)[+];
// write-back in half/float
TYPE y[TN] = Fy;
TYPE ysum = Fysum;
*?(check)px = y / ysum;
}
__global__ void backward(TYPE * X __readonly __noalias __aligned(16),
float scale,
TYPE* DX __readonly __noalias __aligned(16),
int* LUT,
int sizemax,
long stride_zx __multipleof(BLOCK),
long stride_zdx __multipleof(BLOCK)) {
int pidhm = get_program_id(0);
int pidz = get_program_id(1);
// create index ranges
int rxm = pidhm % BLOCK;
int rbm = pidhm / BLOCK;
int rxn[TN] = (0 ... TN) % BLOCK;
int rbn[TN] = (0 ... TN) / BLOCK;
// extract information from look-up table
int* header = LUT + rbm * 2;
int size = *(header + 0);
int offset = *(header + 1);
// bounds checking on lut
bool check[TN] = rbn < size;
int rbmn[TN] = check ? rbn : size - 1;
// initialize pointers to block-sparse input
long blockid[TN] = *(LUT + offset + rbmn*4);
TYPE* px[TN] = X + pidz * stride_zx
+ blockid * BLOCK * BLOCK
+ rxm * BLOCK
+ rxn;
TYPE* pdx[TN] = DX + pidz * stride_zdx
+ blockid * BLOCK * BLOCK
+ rxm * BLOCK
+ rxn;
// compute fused softmax backward
TYPE x[TN] = check ? *px : 0;
TYPE dx[TN] = check ? *pdx : 0;
float Fdx[TN] = dx;
float Fx[TN] = x;
float Fxdx[TN] = Fdx*Fx;
float Fxdxsum = Fxdx[+];
float Fy[TN] = Fx * (Fdx - Fxdxsum) * scale;
TYPE y[TN] = Fy;
// write-back
*? (check)pdx = y;
}

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@@ -0,0 +1,177 @@
import triton
import torch
import os
fwd_src = triton.read(os.path.join(os.path.dirname(__file__), 'softmax.c'),
kernel_names=['forward'])
fwd_kernels = dict()
bwd_src = triton.read(os.path.join(os.path.dirname(__file__), 'softmax.c'),
kernel_names=['backward'])
bwd_kernels = dict()
class _softmax(torch.autograd.Function):
@staticmethod
def make_lut(layout, block, device):
_empty = torch.tensor([], dtype=torch.int64, device=layout.device)
sizes = _empty.clone()
# sizes along rows
for h in range(layout.shape[0]):
sizes = torch.cat((sizes, layout[h,:,:].sum(-1)))
# offsets in block format
offsets = torch.zeros_like(sizes)
offsets[1:] = torch.cumsum(sizes[:-1], dim=0)
# block indices
idx = torch.arange(layout.sum())
head = layout.nonzero(as_tuple=False)[:, 0]
rows = layout.nonzero(as_tuple=False)[:, 1]
columns = layout.nonzero(as_tuple=False)[:, 2]
core = torch.stack((idx, columns, rows, head), dim=1).view(-1)
# construct look-up table
offsets = offsets*4 + 2*sizes.numel()
header = torch.stack((sizes, offsets), dim=1).view(-1)
lut = torch.cat((header, core)).type(torch.int32).to(device)
return lut, int(sizes.max())
@staticmethod
def make_kernel(cache, src, max_k, device, dtype, block, apply_scale, apply_rpe, apply_kp_mask, apply_attn_mask, kp_mask_mode, attn_mask_mode):
if max_k >= 32768:
raise NotImplementedError('Reductions larger than 32768 elements '\
'are not yet implemented')
num_warps = 4 if max_k < 512 else (8 if max_k < 2048 else 16)
pad = num_warps * 32 * 2
TN = (int(max_k) + pad-1)//pad * pad
# just-in-time compile kernel
key = (block, device, dtype, num_warps, TN, apply_scale, apply_rpe, apply_kp_mask, apply_attn_mask, kp_mask_mode, attn_mask_mode)
if key not in cache:
defines = {'TM': [1], 'TN': [TN], 'TYPE': dtype, 'BLOCK': block,
'INFINITY': {torch.float32: 'F32_INFINITY',
torch.float16: 'F16_INFINITY'}[dtype]}
if apply_scale:
defines['APPLY_SCALE'] = True
if apply_rpe:
defines['APPLY_RPE'] = True
if apply_kp_mask:
defines['APPLY_KP_MASK'] = True
if kp_mask_mode == 'mul':
defines['KP_MASK_MUL'] = True
if apply_attn_mask:
defines['APPLY_ATTN_MASK'] = True
if attn_mask_mode == 'mul':
defines['ATTN_MASK_MUL'] = True
kernel = triton.kernel(src, device=device, defines=defines, num_warps=[num_warps])
cache[key] = kernel
return cache[key]
@staticmethod
def forward(ctx, x, scale, rpe, key_padding_mask, attn_mask, kp_mask_mode, attn_mask_mode,
spdims, block, lut, maxlut, bench, time):
apply_scale = False if scale == 1.0 else True
# handle None rpe
if rpe is None:
apply_rpe = False
stride_zrpe, stride_hrpe, stride_srpe = 0, 0, 0
rpe = torch.empty(0, dtype=x.dtype, device=x.device)
else:
apply_rpe = True
stride_zrpe, stride_hrpe, stride_srpe = rpe.stride(0), rpe.stride(1), rpe.stride(2)
# handle None key_padding_mask
if key_padding_mask is None:
apply_kp_mask = False
stride_zkpm = 0
key_padding_mask = torch.empty(0, dtype=x.dtype, device=x.device)
else:
apply_kp_mask = True
stride_zkpm = key_padding_mask.stride(0)
# handle None attention_mask
if attn_mask is None:
apply_attn_mask = False
stride_zattnm = 0
attn_mask = torch.empty(0, dtype=x.dtype, device=x.device)
else:
apply_attn_mask = True
stride_zattnm = attn_mask.stride(0)
# run kernel
kernel = _softmax.make_kernel(fwd_kernels, fwd_src, maxlut*block, x.device, x.dtype, block,
apply_scale, apply_rpe, apply_kp_mask, apply_attn_mask,
kp_mask_mode, attn_mask_mode)
M = x.shape[0]
grid = lambda opt: [triton.cdiv(spdims[0] * spdims[1] * block, opt.TM), M]
# run kernel
time[0] = kernel(x.data_ptr(), scale, lut.data_ptr(), rpe.data_ptr(), key_padding_mask.data_ptr(), attn_mask.data_ptr(),\
maxlut,\
x.stride(0),\
stride_zrpe, stride_hrpe, stride_srpe,\
stride_zkpm, stride_zattnm,\
grid=grid)
# save to context
ctx.mark_dirty(x)
ctx.save_for_backward(x, lut)
ctx.spdims = spdims
ctx.block = block
ctx.maxlut = maxlut
ctx.scale = scale
ctx.apply_scale = apply_scale
ctx.apply_rpe = apply_rpe
ctx.apply_kp_mask = apply_kp_mask
ctx.apply_attn_mask = apply_attn_mask
ctx.kp_mask_mode = kp_mask_mode
ctx.attn_mask_mode = attn_mask_mode
return x
@staticmethod
def backward(ctx, dx):
# retrieve from context
x, lut = ctx.saved_tensors
# run kernel
kernel = _softmax.make_kernel(bwd_kernels, bwd_src, ctx.maxlut*ctx.block, x.device, x.dtype, ctx.block,
ctx.apply_scale, ctx.apply_rpe, ctx.apply_kp_mask, ctx.apply_attn_mask,
ctx.kp_mask_mode, ctx.attn_mask_mode)
M = x.shape[0]
grid = lambda opt: [triton.cdiv(ctx.spdims[0] * ctx.spdims[1] * ctx.block, opt.TM), M]
kernel(x.data_ptr(), ctx.scale, dx.data_ptr(), lut.data_ptr(), ctx.maxlut, x.stride(0), dx.stride(0), grid=grid)
return dx, None, None, None, None, None, None, None, None, None, None, None, None, None, None
class softmax:
apply_softmax = _softmax.apply
def make_lut(self, device):
key = (device, )
if key not in self.lut_cache:
self.lut_cache[key] = _softmax.make_lut(self.layout, self.block, device)
return self.lut_cache[key]
def __init__(self, layout, block, bench = False):
self.spdims = layout.shape
self.layout = layout
self.block = block
self.bench = bench
self.lut_cache = dict()
def __call__(self, x, scale = 1., rpe = None, key_padding_mask = None, attn_mask = None,
key_padding_mask_mode='add', attn_mask_mode='add'):
time_y = [None]
if rpe is not None and rpe.dtype != x.dtype:
raise ValueError('relative position embedding must be %s' % x.dtype)
if attn_mask is not None and attn_mask.dtype != x.dtype:
raise ValueError('Attention mask must be %s' % x.dtype)
if key_padding_mask is not None and key_padding_mask.dtype != x.dtype:
raise ValueError('Key padding mask must be %s' % x.dtype)
lut, maxlut = self.make_lut(x.device)
x = softmax.apply_softmax(x, scale, rpe, key_padding_mask, attn_mask,
key_padding_mask_mode, attn_mask_mode,
self.spdims, self.block,
lut,
maxlut, self.bench, time_y)
return x