File size: 4,271 Bytes
72268ee |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 |
from logging import getLogger
import torch
import torch.nn as nn
logger = getLogger(__name__)
def quantize(x, scale, zero, maxq):
if maxq < 0:
return (x > scale / 2).float() * scale + (x < zero / 2).float() * zero
q = torch.clamp(torch.round(x / scale) + zero, 0, maxq)
return scale * (q - zero)
class Quantizer(nn.Module):
def __init__(self, shape=1):
super(Quantizer, self).__init__()
self.register_buffer('maxq', torch.tensor(0))
self.register_buffer('scale', torch.zeros(shape))
self.register_buffer('zero', torch.zeros(shape))
def configure(
self,
bits, perchannel=False, sym=True,
mse=False, norm=2.4, grid=100, maxshrink=.8,
trits=False
):
self.maxq = torch.tensor(2 ** bits - 1)
self.perchannel = perchannel
self.sym = sym
self.mse = mse
self.norm = norm
self.grid = grid
self.maxshrink = maxshrink
if trits:
self.maxq = torch.tensor(-1)
def find_params(self, x, weight=False):
dev = x.device
self.maxq = self.maxq.to(dev)
shape = x.shape
if self.perchannel:
if weight:
x = x.flatten(1)
else:
if len(shape) == 4:
x = x.permute([1, 0, 2, 3])
x = x.flatten(1)
if len(shape) == 3:
x = x.reshape((-1, shape[-1])).t()
if len(shape) == 2:
x = x.t()
else:
x = x.flatten().unsqueeze(0)
tmp = torch.zeros(x.shape[0], device=dev)
xmin = torch.minimum(x.min(1)[0], tmp)
xmax = torch.maximum(x.max(1)[0], tmp)
if self.sym:
xmax = torch.maximum(torch.abs(xmin), xmax)
tmp = xmin < 0
if torch.any(tmp):
xmin[tmp] = -xmax[tmp]
tmp = (xmin == 0) & (xmax == 0)
xmin[tmp] = -1
xmax[tmp] = +1
if self.maxq < 0:
self.scale = xmax
self.zero = xmin
else:
self.scale = (xmax - xmin) / self.maxq
if self.sym:
self.zero = torch.full_like(self.scale, (self.maxq + 1) / 2)
else:
self.zero = torch.round(-xmin / self.scale)
if self.mse:
best = torch.full([x.shape[0]], float('inf'), device=dev)
for i in range(int(self.maxshrink * self.grid)):
p = 1 - i / self.grid
xmin1 = p * xmin
xmax1 = p * xmax
scale1 = (xmax1 - xmin1) / self.maxq
zero1 = torch.round(-xmin1 / scale1) if not self.sym else self.zero
q = quantize(x, scale1.unsqueeze(1), zero1.unsqueeze(1), self.maxq)
q -= x
q.abs_()
q.pow_(self.norm)
err = torch.sum(q, 1)
tmp = err < best
if torch.any(tmp):
best[tmp] = err[tmp]
self.scale[tmp] = scale1[tmp]
self.zero[tmp] = zero1[tmp]
if not self.perchannel:
if weight:
tmp = shape[0]
else:
tmp = shape[1] if len(shape) != 3 else shape[2]
self.scale = self.scale.repeat(tmp)
self.zero = self.zero.repeat(tmp)
if weight:
shape = [-1] + [1] * (len(shape) - 1)
self.scale = self.scale.reshape(shape)
self.zero = self.zero.reshape(shape)
return
if len(shape) == 4:
self.scale = self.scale.reshape((1, -1, 1, 1))
self.zero = self.zero.reshape((1, -1, 1, 1))
if len(shape) == 3:
self.scale = self.scale.reshape((1, 1, -1))
self.zero = self.zero.reshape((1, 1, -1))
if len(shape) == 2:
self.scale = self.scale.unsqueeze(0)
self.zero = self.zero.unsqueeze(0)
def quantize(self, x):
if self.ready():
return quantize(x, self.scale, self.zero, self.maxq)
return x
def enabled(self):
return self.maxq > 0
def ready(self):
return torch.all(self.scale != 0)
__all__ = ["Quantizer"]
|