[Perf]: CFG parallel abstraction (#851)

Signed-off-by: Didan Deng <33117903+wtomin@users.noreply.github.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

docs/user_guide/examples/offline_inference/image_to_image.md

@@ -47,6 +47,7 @@ Key arguments:
 - `--image`: path(s) to the source image(s) (PNG/JPG, converted to RGB). Can specify multiple images.
 - `--prompt` / `--negative_prompt`: text description (string).
 - `--cfg_scale`: true classifier-free guidance scale (default: 4.0). Classifier-free guidance is enabled by setting cfg_scale > 1 and providing a negative_prompt. Higher guidance scale encourages images closely linked to the text prompt, usually at the expense of lower image quality.
+- `--cfg_parallel_size`: the number of devices to run CFG Parallel. CFG Parallel is valid only if classifier-free guidance is enabled and `cfg_parallel_size` is set to 2.
 - `--guidance_scale`: guidance scale for guidance-distilled models (default: 1.0, disabled). Unlike classifier-free guidance (--cfg_scale), guidance-distilled models take the guidance scale directly as an input parameter. Enabled when guidance_scale > 1. Ignored when not using guidance-distilled models.
 - `--num_inference_steps`: diffusion sampling steps (more steps = higher quality, slower).
 - `--output`: path to save the generated PNG.

docs/user_guide/examples/offline_inference/image_to_video.md

@@ -52,6 +52,7 @@ Key arguments:
 - `--num_frames`: Number of frames (default 81).
 - `--guidance_scale` and `--guidance_scale_high`: CFG scale (applied to low/high-noise stages for MoE).
 - `--negative_prompt`: Optional list of artifacts to suppress.
+- `--cfg_parallel_size`: the number of devices to run CFG Parallel. CFG Parallel is valid only if classifier-free guidance is enabled and `cfg_parallel_size` is set to 2.
 - `--boundary_ratio`: Boundary split ratio for two-stage MoE models.
 - `--flow_shift`: Scheduler flow shift (5.0 for 720p, 12.0 for 480p).
 - `--num_inference_steps`: Number of denoising steps (default 50).

docs/user_guide/examples/offline_inference/text_to_image.md

@@ -95,6 +95,7 @@ Key arguments:
 - `--prompt`: text description (string).
 - `--seed`: integer seed for deterministic sampling.
 - `--cfg_scale`: true CFG scale (model-specific guidance strength).
+- `--cfg_parallel_size`: the number of devices to run CFG Parallel. CFG Parallel is valid only if classifier-free guidance is enabled and `cfg_parallel_size` is set to 2.
 - `--num_images_per_prompt`: number of images to generate per prompt (saves as `output`, `output_1`, ...).
 - `--num_inference_steps`: diffusion sampling steps (more steps = higher quality, slower).
 - `--height/--width`: output resolution (defaults 1024x1024).

docs/user_guide/examples/offline_inference/text_to_video.md

@@ -28,6 +28,7 @@ Key arguments:
 - `--num_frames`: Number of frames (Wan default is 81).
 - `--guidance_scale` and `--guidance_scale_high`: CFG scale (applied to low/high)..
 - `--negative_prompt`: optional list of artifacts to suppress (the PR demo used a long Chinese string).
+- `--cfg_parallel_size`: the number of devices to run CFG Parallel. CFG Parallel is valid only if classifier-free guidance is enabled and `cfg_parallel_size` is set to 2.
 - `--boundary_ratio`: Boundary split ratio for low/high DiT.
 - `--fps`: frames per second for the saved MP4 (requires `diffusers` export_to_video).
 - `--output`: path to save the generated video.