stable-diffusion-webui/modules/lowvram.py

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import torch
from modules import devices
module_in_gpu = None
cpu = torch.device("cpu")
def send_everything_to_cpu():
global module_in_gpu
if module_in_gpu is not None:
module_in_gpu.to(cpu)
module_in_gpu = None
def setup_for_low_vram(sd_model, use_medvram):
sd_model.lowvram = True
parents = {}
def send_me_to_gpu(module, _):
"""send this module to GPU; send whatever tracked module was previous in GPU to CPU;
we add this as forward_pre_hook to a lot of modules and this way all but one of them will
be in CPU
"""
global module_in_gpu
module = parents.get(module, module)
if module_in_gpu == module:
return
if module_in_gpu is not None:
module_in_gpu.to(cpu)
module.to(devices.device)
module_in_gpu = module
# see below for register_forward_pre_hook;
# first_stage_model does not use forward(), it uses encode/decode, so register_forward_pre_hook is
# useless here, and we just replace those methods
first_stage_model = sd_model.first_stage_model
first_stage_model_encode = sd_model.first_stage_model.encode
first_stage_model_decode = sd_model.first_stage_model.decode
def first_stage_model_encode_wrap(x):
send_me_to_gpu(first_stage_model, None)
return first_stage_model_encode(x)
def first_stage_model_decode_wrap(z):
send_me_to_gpu(first_stage_model, None)
return first_stage_model_decode(z)
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to_remain_in_cpu = [
(sd_model, 'first_stage_model'),
(sd_model, 'depth_model'),
(sd_model, 'embedder'),
(sd_model, 'model'),
(sd_model, 'embedder'),
]
is_sdxl = hasattr(sd_model, 'conditioner')
is_sd2 = not is_sdxl and hasattr(sd_model.cond_stage_model, 'model')
if is_sdxl:
to_remain_in_cpu.append((sd_model, 'conditioner'))
elif is_sd2:
to_remain_in_cpu.append((sd_model.cond_stage_model, 'model'))
else:
to_remain_in_cpu.append((sd_model.cond_stage_model, 'transformer'))
# remove several big modules: cond, first_stage, depth/embedder (if applicable), and unet from the model
stored = []
for obj, field in to_remain_in_cpu:
module = getattr(obj, field, None)
stored.append(module)
setattr(obj, field, None)
# send the model to GPU.
sd_model.to(devices.device)
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# put modules back. the modules will be in CPU.
for (obj, field), module in zip(to_remain_in_cpu, stored):
setattr(obj, field, module)
# register hooks for those the first three models
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if is_sdxl:
sd_model.conditioner.register_forward_pre_hook(send_me_to_gpu)
elif is_sd2:
sd_model.cond_stage_model.model.register_forward_pre_hook(send_me_to_gpu)
sd_model.cond_stage_model.model.token_embedding.register_forward_pre_hook(send_me_to_gpu)
parents[sd_model.cond_stage_model.model] = sd_model.cond_stage_model
parents[sd_model.cond_stage_model.model.token_embedding] = sd_model.cond_stage_model
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else:
sd_model.cond_stage_model.transformer.register_forward_pre_hook(send_me_to_gpu)
parents[sd_model.cond_stage_model.transformer] = sd_model.cond_stage_model
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sd_model.first_stage_model.register_forward_pre_hook(send_me_to_gpu)
sd_model.first_stage_model.encode = first_stage_model_encode_wrap
sd_model.first_stage_model.decode = first_stage_model_decode_wrap
if sd_model.depth_model:
sd_model.depth_model.register_forward_pre_hook(send_me_to_gpu)
if sd_model.embedder:
sd_model.embedder.register_forward_pre_hook(send_me_to_gpu)
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if use_medvram:
sd_model.model.register_forward_pre_hook(send_me_to_gpu)
else:
diff_model = sd_model.model.diffusion_model
# the third remaining model is still too big for 4 GB, so we also do the same for its submodules
# so that only one of them is in GPU at a time
stored = diff_model.input_blocks, diff_model.middle_block, diff_model.output_blocks, diff_model.time_embed
diff_model.input_blocks, diff_model.middle_block, diff_model.output_blocks, diff_model.time_embed = None, None, None, None
sd_model.model.to(devices.device)
diff_model.input_blocks, diff_model.middle_block, diff_model.output_blocks, diff_model.time_embed = stored
# install hooks for bits of third model
diff_model.time_embed.register_forward_pre_hook(send_me_to_gpu)
for block in diff_model.input_blocks:
block.register_forward_pre_hook(send_me_to_gpu)
diff_model.middle_block.register_forward_pre_hook(send_me_to_gpu)
for block in diff_model.output_blocks:
block.register_forward_pre_hook(send_me_to_gpu)
def is_enabled(sd_model):
return getattr(sd_model, 'lowvram', False)