Optimizations to PAG and t2i-zero

[drhead]

I've made a few optimizations to PAG and t2i-zero.

For PAG, you might not notice the changes too much speed-wise, it's already unavoidably very slow. One tensor was being created on CPU then moved to device. This was a problem when using some proposed performance optimizations for A1111 particularly (https://github.com/AUTOMATIC1111/stable-diffusion-webui/pull/15821). Now these changes won't break PAG.

For t2i-zero, the changes are more substantial. There were a lot of forced device syncs happening. Summarizing the changes:

• 🗞️💥 A number of scalar values were being initialized as CUDA tensors then used as control flow. That means aten::item is called on them, which forces a device sync. None of them needed to be CUDA tensors to do anything else they were doing so I set them to all be CPU tensors, which removed the blocks.
• 🗞️💥 When token_indices was None or [], this was creating a list of all tokens using torch.tensor(list(range(1, token_count.item()))), which causes a device sync for every single token in the sequence (!). torch.arange(1, token_count, device=output.device) is much more suitable, and creates the tensor directly on-device.
• 🗞️💥 This one is Torchvision's fault. GaussianBlur creates the kernels every time it is run on CPU and then moves them to the GPU, which -- you guessed it -- causes a forced device sync. I submitted a patch to the torchvision repo. You'll still have that forced device sync there in the mean time. I changed it so that the module is not initialized multiple times every inference step as part of troubleshooting this -- unfortunately the kernels are created every call regardless, so this doesn't fix the problem directly and probably isn't even necessary, but I would say keep it because it is probably best that we don't initialize modules inside of a forward pass anyways. I did suggest caching the kernels, so it might help in the future.

Once the associated torchvision patch and the a1111 optimizations go through, you can expect t2i-zero to run with almost no significant overhead compared to having it disabled.

[v0xie]

This is great, thanks so much.

I am getting an error when I run with CTNMS enabled, perhaps related to making ema_factor cpu?

    Traceback (most recent call last):
      File "F:\stablediffusion\stable-diffusion-webui\modules\call_queue.py", line 57, in f
        res = list(func(*args, **kwargs))
      File "F:\stablediffusion\stable-diffusion-webui\modules\call_queue.py", line 36, in f
        res = func(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\modules\txt2img.py", line 109, in txt2img
        processed = processing.process_images(p)
      File "F:\stablediffusion\stable-diffusion-webui\modules\processing.py", line 839, in process_images
        res = process_images_inner(p)
      File "F:\stablediffusion\stable-diffusion-webui\extensions\sd-webui-controlnet\scripts\batch_hijack.py", line 59, in processing_process_images_hijack
        return getattr(processing, '__controlnet_original_process_images_inner')(p, *args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\modules\processing.py", line 975, in process_images_inner
        samples_ddim = p.sample(conditioning=p.c, unconditional_conditioning=p.uc, seeds=p.seeds, subseeds=p.subseeds, subseed_strength=p.subseed_strength, prompts=p.prompts)
      File "F:\stablediffusion\stable-diffusion-webui\modules\processing.py", line 1322, in sample
        samples = self.sampler.sample(self, x, conditioning, unconditional_conditioning, image_conditioning=self.txt2img_image_conditioning(x))
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_samplers_kdiffusion.py", line 218, in sample
        samples = self.launch_sampling(steps, lambda: self.func(self.model_wrap_cfg, x, extra_args=self.sampler_extra_args, disable=False, callback=self.callback_state, **extra_params_kwargs))
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_samplers_common.py", line 272, in launch_sampling
        return func()
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_samplers_kdiffusion.py", line 218, in <lambda>
        samples = self.launch_sampling(steps, lambda: self.func(self.model_wrap_cfg, x, extra_args=self.sampler_extra_args, disable=False, callback=self.callback_state, **extra_params_kwargs))
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\utils\_contextlib.py", line 115, in decorate_context
        return func(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\k-diffusion\k_diffusion\sampling.py", line 626, in sample_dpmpp_2m_sde
        denoised = model(x, sigmas[i] * s_in, **extra_args)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1518, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1527, in _call_impl
        return forward_call(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_samplers_cfg_denoiser.py", line 237, in forward
        x_out = self.inner_model(x_in, sigma_in, cond=make_condition_dict(cond_in, image_cond_in))
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1518, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1527, in _call_impl
        return forward_call(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\k-diffusion\k_diffusion\external.py", line 112, in forward
        eps = self.get_eps(input * c_in, self.sigma_to_t(sigma), **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\k-diffusion\k_diffusion\external.py", line 138, in get_eps
        return self.inner_model.apply_model(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_models_xl.py", line 43, in apply_model
        return self.model(x, t, cond)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1518, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1527, in _call_impl
        return forward_call(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_hijack_utils.py", line 22, in <lambda>
        setattr(resolved_obj, func_path[-1], lambda *args, **kwargs: self(*args, **kwargs))
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_hijack_utils.py", line 34, in __call__
        return self.__sub_func(self.__orig_func, *args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_hijack_unet.py", line 48, in apply_model
        result = orig_func(self, x_noisy.to(devices.dtype_unet), t.to(devices.dtype_unet), cond, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\generative-models\sgm\modules\diffusionmodules\wrappers.py", line 28, in forward
        return self.diffusion_model(
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1518, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1527, in _call_impl
        return forward_call(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\modules\sd_unet.py", line 91, in UNetModel_forward
        return original_forward(self, x, timesteps, context, *args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\generative-models\sgm\modules\diffusionmodules\openaimodel.py", line 993, in forward
        h = module(h, emb, context)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1518, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1527, in _call_impl
        return forward_call(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\generative-models\sgm\modules\diffusionmodules\openaimodel.py", line 100, in forward
        x = layer(x, context)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1518, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1527, in _call_impl
        return forward_call(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\generative-models\sgm\modules\attention.py", line 627, in forward
        x = block(x, context=context[i])
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1518, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1527, in _call_impl
        return forward_call(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\generative-models\sgm\modules\attention.py", line 459, in forward
        return checkpoint(
      File "F:\stablediffusion\stable-diffusion-webui\repositories\generative-models\sgm\modules\diffusionmodules\util.py", line 167, in checkpoint
        return func(*inputs)
      File "F:\stablediffusion\stable-diffusion-webui\repositories\generative-models\sgm\modules\attention.py", line 478, in _forward
        self.attn2(
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1518, in _wrapped_call_impl
        return self._call_impl(*args, **kwargs)
      File "F:\stablediffusion\stable-diffusion-webui\venv\lib\site-packages\torch\nn\modules\module.py", line 1579, in _call_impl
        hook_result = hook(self, args, kwargs, result)
      File "F:\stablediffusion\stable-diffusion-webui\extensions\sd-webui-incantations\scripts\t2i_zero.py", line 518, in cross_token_non_maximum_suppression
        ema = ema_factor * ema + (1 - ema_factor) * suppressed_attention_map
    RuntimeError: Expected all tensors to be on the same device, but found at least two devices, cuda:0 and cpu!

[drhead]

I am getting an error when I run with CTNMS enabled, perhaps related to making ema_factor cpu?

Yeah... those are probably better off as python scalars. I don't have time to test it now but what I just committed should be correct. I can look over it again tomorrow if needed.

[v0xie]

Works great. Thanks again!