complete contextmanager method for keeping only one unet in GPU during training or inference

README.md

@@ -411,8 +411,8 @@ Offer training wrappers
 - [x] build the cascading ddpm by having Decoder class manage multiple unets at different resolutions
 - [x] add efficient attention in unet
 - [x] be able to finely customize what to condition on (text, image embed) for specific unet in the cascade (super resolution ddpms near the end may not need too much conditioning)
+- [x] offload unets not being trained on to CPU for memory efficiency (for training each resolution unets separately)
 - [ ] build out latent diffusion architecture in separate file, as it is not faithful to dalle-2 (but offer it as as setting)
-- [ ] offload unets not being trained on to CPU for memory efficiency (for training each resolution unets separately)
 - [ ] become an expert with unets, cleanup unet code, make it fully configurable, port all learnings over to https://github.com/lucidrains/x-unet
 - [ ] train on a toy task, offer in colab
 

dalle2_pytorch/dalle2_pytorch.py

@@ -2,6 +2,7 @@ import math
 from tqdm import tqdm
 from inspect import isfunction
 from functools import partial
+from contextlib import contextmanager
 
 import torch
 import torch.nn.functional as F
@@ -1141,6 +1142,20 @@ class Decoder(nn.Module):
         self.register_buffer('posterior_mean_coef1', betas * torch.sqrt(alphas_cumprod_prev) / (1. - alphas_cumprod))
         self.register_buffer('posterior_mean_coef2', (1. - alphas_cumprod_prev) * torch.sqrt(alphas) / (1. - alphas_cumprod))
 
+    @contextmanager
+    def one_unet_in_gpu(self, unet_number):
+        assert 0 < unet_number <= len(self.unets)
+        index = unet_number - 1
+        self.cuda()
+        self.unets.cpu()
+
+        unet = self.unets[index]
+        unet.cuda()
+
+        yield
+
+        self.unets.cpu()
+
     def get_text_encodings(self, text):
         text_encodings = self.clip.text_transformer(text)
         return text_encodings[:, 1:]
@@ -1245,7 +1260,9 @@ class Decoder(nn.Module):
         text_encodings = self.get_text_encodings(text) if exists(text) else None
 
         img = None
-        for unet, image_size in tqdm(zip(self.unets, self.image_sizes)):
+
+        for ind, (unet, image_size) in tqdm(enumerate(zip(self.unets, self.image_sizes))):
+            with self.one_unet_in_gpu(ind + 1):
                 shape = (batch_size, channels, image_size, image_size)
                 img = self.p_sample_loop(unet, shape, image_embed = image_embed, text_encodings = text_encodings, cond_scale = cond_scale, lowres_cond_img = img)
 

setup.py

@@ -10,7 +10,7 @@ setup(
       'dream = dalle2_pytorch.cli:dream'
     ],
   },
-  version = '0.0.27',
+  version = '0.0.28',
   license='MIT',
   description = 'DALL-E 2',
   author = 'Phil Wang',