X-Git-Url: https://fleuret.org/cgi-bin/gitweb/gitweb.cgi?a=blobdiff_plain;f=mygpt.py;h=492a9bb96872e93f99ea9d9609ba64fe557c57fa;hb=e3d5af800ccd197580265709c4499bf281beecb8;hp=33c6fee0f89f60f53014d9b8defebf38a7d5f1b7;hpb=a3abd0f58cfb2f2448c82db836093d20dc2954f2;p=mygptrnn.git diff --git a/mygpt.py b/mygpt.py index 33c6fee..492a9bb 100755 --- a/mygpt.py +++ b/mygpt.py @@ -10,6 +10,8 @@ # with a caching mechanism for keys and values to avoid a O(N^3) cost # for auto-regression. +# This implementation is equipped with RNN layers to replace the MHA + import math, warnings import torch, einops @@ -37,7 +39,7 @@ import ffutils # 1 for the successive tokens. # # Modules able to process brackets may implement a cache that is -# resetted when the input bracket starts at t=0 +# resetted when init_cache is True class BracketedSequence: @@ -124,7 +126,6 @@ class AddPositionalEncoding(nn.Module): import pscan - # X is /.../xTxD A is /.../xT Y_init is /.../xD @@ -145,6 +146,18 @@ def pscan_dim(A, X, Y_init, dim=-2): return Y +def pscan_rgrad(grad_Y, A, X, Y_init, dim=-2, eps=1e-2): + with torch.no_grad(): + s_A, s_X = 0, 0 + for t in range(X.size(dim) - 1, 0, -1): + delta = (grad_Y[t] - s_A) / A[t].grad + s_A += A[t].grad * delta + A[t].grad = delta + delta = (grad_Y[t] - s_X) / X[t].grad + s_X += X[t].grad * delta + X[t].grad = delta + + def pscan_shape(A, X, Y_init): s = X.size() A = A.reshape(-1, s[-2]) @@ -188,6 +201,8 @@ class DumbRec(nn.Module): nb_lines, attention_dropout=0.0, len_max=1e5, + logger=print, + **kwargs, ): super().__init__() @@ -317,6 +332,8 @@ class KVRec(nn.Module): nb_lines, attention_dropout=0.0, len_max=1e5, + logger=print, + **kwargs, ): super().__init__() @@ -441,6 +458,11 @@ class KVRec(nn.Module): ############################## +# Returns a tensor with an additional index at rank win_dim, that move +# along the same dimension as dim, on a domain {0...win_size-1}, and +# dim is restricted on a domain reduced by win_size-1 values. + + def moving_window(x, dim, win_dim, win_size): size, stride = x.size(), x.stride() size = size[:dim] + (size[dim] - win_size + 1,) + size[dim + 1 :] @@ -464,32 +486,61 @@ class Caterpillar(nn.Module): caterpillar_height, attention_dropout=0.0, len_max=1e5, + logger=print, + **kwargs, ): super().__init__() warnings.warn("Caterpillar", RuntimeWarning) - def randw(*d): - return nn.Parameter(torch.randn(*d) / math.sqrt(d[-1])) + def randw(*d, amplitude=None): + if amplitude is None: + amplitude = 1 / math.sqrt(d[-1]) + return nn.Parameter(amplitude * torch.randn(*d)) self.caterpillar_length = caterpillar_length self.caterpillar_height = caterpillar_height self.attention_dropout = attention_dropout + ###################################################################### + # sup_args + + x = kwargs.get("gate_dropout") + if x is None: + self.proba_gate_dropout = 0.0 + else: + self.proba_gate_dropout = float(x) + + logger(f"self.proba_gate_dropout {self.proba_gate_dropout}") + + x = kwargs.get("default_bg") + if x is None: + default_bg = -math.log(caterpillar_height - 1) + else: + default_bg = float(x) + + logger(f"default_bg {default_bg}") + + ###################################################################### + self.w_G = randw(nb_heads, caterpillar_height, dim_model) - self.b_G = nn.Parameter( - torch.full( - (nb_heads, caterpillar_height), -math.log(caterpillar_height - 1) - ) - ) + self.b_G = nn.Parameter(torch.full((nb_heads, caterpillar_height), default_bg)) self.w_K = randw(nb_heads, dim_qk, dim_model) self.w_V = randw(nb_heads, dim_v, dim_model) self.w_Q = randw(nb_heads, dim_qk, dim_model) self.w_O = randw(dim_v * nb_heads, dim_model) - self.init_K_rec = randw(caterpillar_height, caterpillar_length, dim_qk) - self.init_V_rec = randw(caterpillar_height, caterpillar_length, dim_v) + self.init_K_rec = randw( + caterpillar_height, + caterpillar_length, + dim_qk, + ) + self.init_V_rec = randw( + caterpillar_height, + caterpillar_length, + dim_v, + ) def reset_inner_loss(self): self.acc_attention = 0 @@ -507,68 +558,111 @@ class Caterpillar(nn.Module): N = bs.x.size(0) T = bs.x.size(1) + H = self.w_V.size(0) DV = self.w_V.size(1) DK = self.w_K.size(1) - Dout = self.w_O.size(1) - CH = self.caterpillar_height - CL = self.caterpillar_length + DM = self.w_O.size(1) + R = self.caterpillar_height + L = self.caterpillar_length assert ( - t0 >= CL and (t1 - t0) % CL == 0 + t0 >= L and (t1 - t0) % L == 0 ), f"bs.first should be greater than caterpillar_length, and bs.nb should be a multiple of caterpillar_length" + # We cache values to deal efficiently with auto-regression + if bs.init_cache: - self.rec_V = X.new_zeros(N, CH, T, DV) - self.rec_K = X.new_zeros(N, CH, T, DK) + self.rec_V = X.new_zeros(N, R, T, DV) + self.rec_K = X.new_zeros(N, R, T, DK) # We start the recurrent sequences with optimizable # initial values. No idea if it helps. - self.rec_V[:, :, t0 - CL : t0] = self.init_V_rec[None, :, :, :] - self.rec_K[:, :, t0 - CL : t0] = self.init_K_rec[None, :, :, :] + self.rec_V[:, :, t0 - L : t0, :] = self.init_V_rec[None, :, :, :] + self.rec_K[:, :, t0 - L : t0, :] = self.init_K_rec[None, :, :, :] + + self.cache_Y = X.new_zeros(N, T, DM) - self.cache_Y = X.new_zeros(N, T, Dout) + V = torch.einsum("ntc,hdc->nhtd", X, self.w_V) + K = torch.einsum("ntc,hdc->nhtd", X, self.w_K) ###################################################################### # Compute the recurrent state # This is the Gating sequence that modulates the storing of - # the new key and value in the CH pairs of the current - # stack. The CH gating values are independent, which means - # that the current K/V could be stored in all the pairs of the + # the new key and value in the R pairs of the current + # stack. There are R independent gating values, which means + # that the current K/V may be stored in multiple pairs of the # recurrent state, or not at all. G = ( - torch.einsum("ntc,hec->nhet", X, self.w_G) + self.b_G[None, :, :, None] + torch.einsum("ntc,hrc->nhrt", X, self.w_G) + self.b_G[None, :, :, None] ).sigmoid() - V = torch.einsum("ntc,hdc->nhtd", X, self.w_V) - K = torch.einsum("ntc,hdc->nhtd", X, self.w_K) + # Clip the gating to avoid values greater than 1 when several + # heads hit the same row + + G = G / G.sum(1, keepdim=True).clamp(min=1) + + ###################################################################### + + def recurrence(G, V, K): + # We prepare the arguments for the parallel scan + + A = 1 - G.sum(1) + + gated_V = torch.einsum("nhrt,nhtd->nrtd", G, V) + gated_K = torch.einsum("nhrt,nhtd->nrtd", G, K) + + # We start from cached values, which matters in inference + + init_rec_V = self.rec_V[:, :, t0 - L : t0] + init_rec_K = self.rec_K[:, :, t0 - L : t0] - # We prepare the arguments for the parallel scan + # Associative scan - A = 1 - G.sum(1) - gated_V = torch.einsum("nhet,nhtd->netd", G, V) - gated_K = torch.einsum("nhet,nhtd->netd", G, K) + # Here there is a trick: Since the stack at position t is + # computed by updating that at position t-L, the parallel + # scan operates with a period of L. To do so we split the + # sequence indexing in two axes, the second of size L, and + # run the parallel scan using the first as the sequence index. - init_rec_V = self.rec_V[:, :, t0 - CL : t0] - init_rec_K = self.rec_K[:, :, t0 - CL : t0] + A = A.unflatten(2, (-1, L)) + gated_V = gated_V.unflatten(2, (-1, L)) + gated_K = gated_K.unflatten(2, (-1, L)) - # Here there is a trick: Since the stack at time t is computed - # by updating that at time t-L, the parallel scan operates - # with a period of L. To do so we split the time indexing in - # two axes, the second of size CL, and run the parallel scan - # using the other alone as the sequence index. + next_V = pscan_dim(A, gated_V, init_rec_V, dim=2) + next_K = pscan_dim(A, gated_K, init_rec_K, dim=2) - A = A.unflatten(2, (-1, CL)) - gated_V = gated_V.unflatten(2, (-1, CL)) - gated_K = gated_K.unflatten(2, (-1, CL)) + next_V = next_V.flatten(2, 3) + next_K = next_K.flatten(2, 3) - next_V = pscan_dim(A, gated_V, init_rec_V, dim=2) - next_K = pscan_dim(A, gated_K, init_rec_K, dim=2) + return next_V, next_K - # Put back the sequence index + ################################################################# - self.rec_V[:, :, t0:t1] = next_V.flatten(2, 3) - self.rec_K[:, :, t0:t1] = next_K.flatten(2, 3) + next_V, next_K = recurrence(G, V, K) + + if self.training and self.proba_gate_dropout > 0.0: + # G is NxHxRxT where r is the caterpillar's row. + + warnings.warn("gate dropout", RuntimeWarning) + + kill = ( + torch.rand(G.size(), device=G.device) <= self.proba_gate_dropout + ).float() + + mask = 1 - kill + + masked_next_V, masked_next_K = recurrence(G * mask, V, K) + + next_V = next_V.detach() + (masked_next_V - masked_next_V.detach()) / ( + 1 - self.proba_gate_dropout + ) + next_K = next_K.detach() + (masked_next_K - masked_next_K.detach()) / ( + 1 - self.proba_gate_dropout + ) + + self.rec_V[:, :, t0:t1] = next_V + self.rec_K[:, :, t0:t1] = next_K ###################################################################### # compute the readout @@ -580,14 +674,14 @@ class Caterpillar(nn.Module): # the column in the caterpillar windowed_V = moving_window( - self.rec_V[:, :, t0 - CL + 1 : t1], dim=2, win_dim=3, win_size=CL + self.rec_V[:, :, t0 - L + 1 : t1], dim=2, win_dim=3, win_size=L ) windowed_K = moving_window( - self.rec_K[:, :, t0 - CL + 1 : t1], dim=2, win_dim=3, win_size=CL + self.rec_K[:, :, t0 - L + 1 : t1], dim=2, win_dim=3, win_size=L ) - # We have an attention score for each of the CHxCL values + # We have an attention score for each of the RxL values ar = torch.einsum( "nhtd,nftld->nhtfl", @@ -629,6 +723,8 @@ class QKVAttention(nn.Module): nb_heads=1, causal=False, attention_dropout=0.0, + logger=print, + **kwargs, ): super().__init__() @@ -716,15 +812,21 @@ class MyGPT(nn.Module): nb_blocks, nb_lines=None, caterpillar_height=None, - dim_rec_v=-1, causal=False, dropout=0.0, len_max=1e5, attention_layer="kvrec", + logger=print, + **kwargs, ): super().__init__() - assert attention_layer in {"mha", "dumbrec", "kvrec", "caterpillar"} + assert attention_layer in { + "mha", + "dumbrec", + "kvrec", + "caterpillar", + }, f"Unknown attention operator {attention_layer}." if attention_layer == "caterpillar": assert nb_lines % caterpillar_height == 0 @@ -752,34 +854,42 @@ class MyGPT(nn.Module): nb_heads=nb_heads, causal=causal, attention_dropout=dropout, + logger=logger, + **kwargs, ) elif attention_layer == "dumbrec": return DumbRec( dim_model=dim_model, dim_qk=dim_keys, - dim_v=dim_rec_v, + dim_v=dim_model // nb_heads, nb_heads=nb_heads, nb_lines=nb_lines, attention_dropout=dropout, + logger=logger, + **kwargs, ) elif attention_layer == "kvrec": return KVRec( dim_model=dim_model, dim_qk=dim_keys, - dim_v=dim_rec_v, + dim_v=dim_model // nb_heads, nb_heads=nb_heads, nb_lines=nb_lines, attention_dropout=dropout, + logger=logger, + **kwargs, ) elif attention_layer == "caterpillar": return Caterpillar( dim_model=dim_model, dim_qk=dim_keys, - dim_v=dim_rec_v, + dim_v=dim_model // nb_heads, nb_heads=nb_heads, caterpillar_length=self.caterpillar_length, caterpillar_height=self.caterpillar_height, attention_dropout=dropout, + logger=logger, + **kwargs, ) else: raise ValueError(f"Unknown attention type {attention_layer}.")