Optimize WAN pipeline: hoist timesteps, batched text encoding, I2V concat/transpose churn reduction, replace prints with max_logging, and fix CFG cache multi-host sharding crashes

Author: Perseus14

src/maxdiffusion/loaders/ltx2_lora_nnx_loader.py

@@ -76,8 +76,6 @@ def translate_fn(nnx_path_str):
     # the merge_fn warns about unmatched keys in each dict, so we only warn about any leftovers
     unmatched_keys = set(h_state_dict) - set(transformer_state_dict) - set(connector_state_dict)
     if unmatched_keys:
-      max_logging.log(
-          f"{len(unmatched_keys)} key(s) in LoRA dictionary routed to no merge target: {unmatched_keys}"
-      )
+      max_logging.log(f"{len(unmatched_keys)} key(s) in LoRA dictionary routed to no merge target: {unmatched_keys}")
 
     return pipeline

src/maxdiffusion/models/quantizations.py

@@ -25,6 +25,7 @@
 import jax.numpy as jnp
 from jax.tree_util import tree_flatten_with_path, tree_unflatten
 from typing import Tuple, Sequence
+from maxdiffusion import max_logging
 
 # Params used to define mixed precision quantization configs
 DEFAULT = "__default__"  # default config
@@ -139,7 +140,7 @@ def _get_quant_config(config):
     else:
       drhs_bits = 8
       drhs_accumulator_dtype = jnp.int32
-      print(config.quantization_local_shard_count)  # -1
+      max_logging.log(config.quantization_local_shard_count)  # -1
       drhs_local_aqt = aqt_config.LocalAqt(contraction_axis_shard_count=config.quantization_local_shard_count)
     return aqt_config.config_v4(
         fwd_bits=8,

src/maxdiffusion/pipelines/wan/wan_pipeline.py

@@ -997,7 +997,8 @@ def _prepare_model_inputs_i2v(
 
     prompt_embeds = jax.device_put(prompt_embeds, data_sharding)
     negative_prompt_embeds = jax.device_put(negative_prompt_embeds, data_sharding)
-    image_embeds = jax.device_put(image_embeds, data_sharding)
+    if image_embeds is not None:
+      image_embeds = jax.device_put(image_embeds, data_sharding)
 
     return prompt_embeds, negative_prompt_embeds, image_embeds, effective_batch_size
 

src/maxdiffusion/pipelines/wan/wan_pipeline_2_1.py

@@ -25,6 +25,7 @@
 import numpy as np
 import time
 from ... import max_utils
+from maxdiffusion import max_logging
 
 
 class WanPipeline2_1(WanPipeline):
@@ -101,6 +102,7 @@ def __call__(
       magcache_K: Optional[int] = None,
       retention_ratio: Optional[float] = None,
       use_kv_cache: bool = False,
+      output_type: str = "pil",
   ):
     config = getattr(self, "config", None)
     if max_sequence_length is None:
@@ -170,6 +172,9 @@ def __call__(
       latents.block_until_ready()
     trace["denoise_total"] = time.perf_counter() - t_denoise_start
 
+    if output_type == "latent":
+      return latents, trace
+
     t_decode_start = time.perf_counter()
     video = self._decode_latents_to_video(latents, trace=trace)
     if hasattr(video, "block_until_ready"):
@@ -222,6 +227,18 @@ def run_inference_2_1(
   do_cfg = guidance_scale > 1.0
   bsz = latents.shape[0]
 
+  data_shards = 1
+  try:
+    if hasattr(latents, "sharding") and hasattr(latents.sharding, "mesh"):
+      data_shards = latents.sharding.mesh.shape["data"] * latents.sharding.mesh.shape.get("fsdp", 1)
+  except Exception:
+    pass
+
+  if use_cfg_cache and do_cfg and bsz % data_shards != 0:
+    max_logging.log(
+        f"Warning: Disabling CFG cache because batch size {bsz} is not divisible by data shards {data_shards}. This often happens with data_parallelism > 1 and per_device_batch_size = 1."
+    )
+    use_cfg_cache = False
   # Resolution-dependent CFG cache config (FasterCache / MixCache guidance)
   if height >= 720:
     # 720p: conservative — protect last 40%, interval=5
@@ -306,10 +323,9 @@ def run_inference_2_1(
   )
 
   scan_diffusion_loop = getattr(config, "scan_diffusion_loop", False) if config else False
+  timesteps = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)
 
   if scan_diffusion_loop and not use_magcache and not use_cfg_cache:
-    timesteps = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)
-
     scheduler_state = scheduler_state.replace(last_sample=jnp.zeros_like(latents), step_index=jnp.array(0, dtype=jnp.int32))
 
     def scan_body(carry, t):
@@ -365,7 +381,7 @@ def scan_body(carry, t):
       profiler = max_utils.Profiler(config)
       profiler.start()
 
-    t = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)[step]
+    t = timesteps[step]
 
     if use_magcache and do_cfg:
       timestep = jnp.broadcast_to(t, bsz * 2 if do_cfg else bsz)

src/maxdiffusion/pipelines/wan/wan_pipeline_2_2.py

@@ -118,6 +118,7 @@ def __call__(
       use_cfg_cache: bool = False,
       use_sen_cache: bool = False,
       use_kv_cache: bool = False,
+      output_type: str = "pil",
   ):
     config = getattr(self, "config", None)
     if max_sequence_length is None:
@@ -203,6 +204,9 @@ def __call__(
       latents.block_until_ready()
     trace["denoise_total"] = time.perf_counter() - t_denoise_start
 
+    if output_type == "latent":
+      return latents, trace
+
     t_decode_start = time.perf_counter()
     video = self._decode_latents_to_video(latents, trace=trace)
     if hasattr(video, "block_until_ready"):
@@ -252,6 +256,19 @@ def run_inference_2_2(
   do_classifier_free_guidance = guidance_scale_low > 1.0 or guidance_scale_high > 1.0
   bsz = latents.shape[0]
 
+  data_shards = 1
+  try:
+    if hasattr(latents, "sharding") and hasattr(latents.sharding, "mesh"):
+      data_shards = latents.sharding.mesh.shape["data"] * latents.sharding.mesh.shape.get("fsdp", 1)
+  except Exception:
+    pass
+
+  if use_cfg_cache and do_classifier_free_guidance and bsz % data_shards != 0:
+    max_logging.log(
+        f"Warning: Disabling CFG cache because batch size {bsz} is not divisible by data shards {data_shards}. This often happens with data_parallelism > 1 and per_device_batch_size = 1."
+    )
+    use_cfg_cache = False
+
   prompt_embeds_combined = (
       jnp.concatenate([prompt_embeds, negative_prompt_embeds], axis=0) if do_classifier_free_guidance else prompt_embeds
   )
@@ -279,6 +296,8 @@ def run_inference_2_2(
     high_transformer = nnx.merge(high_noise_graphdef, high_noise_state, high_noise_rest)
     kv_cache_high, encoder_attention_mask_high = high_transformer.compute_kv_cache(prompt_embeds_combined)
 
+  timesteps = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)
+
   # ── SenCache path (arXiv:2602.24208) ──
   if use_sen_cache and do_classifier_free_guidance:
     timesteps_np = np.array(scheduler_state.timesteps, dtype=np.int32)
@@ -303,16 +322,18 @@ def run_inference_2_2(
     num_train_timesteps = float(scheduler.config.num_train_timesteps)
 
     # SenCache state
-    ref_noise_pred = None  # y^r: cached denoiser output
-    ref_latent = None  # x^r: latent at last cache refresh
-    ref_timestep = 0.0  # t^r: timestep (normalized to [0,1]) at last cache refresh
-    accum_dx = 0.0  # accumulated ||Δx|| since last refresh
-    accum_dt = 0.0  # accumulated |Δt| since last refresh
-    reuse_count = 0  # consecutive cache reuses
-    cache_count = 0
+    ref_noise_pred = jnp.zeros(
+        (bsz * 2, latents.shape[1], latents.shape[2], latents.shape[3], latents.shape[4]), dtype=latents.dtype
+    )
+    ref_latent = jnp.zeros_like(latents)
+    ref_timestep = jnp.array(0.0, dtype=jnp.float32)
+    accum_dx = jnp.array(0.0, dtype=jnp.float32)
+    accum_dt = jnp.array(0.0, dtype=jnp.float32)
+    reuse_count = jnp.array(0, dtype=jnp.int32)
+    cache_count = jnp.array(0, dtype=jnp.int32)
 
     for step in range(num_inference_steps):
-      t = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)[step]
+      t = timesteps[step]
       t_float = float(timesteps_np[step]) / num_train_timesteps  # normalize to [0, 1]
 
       # Select transformer and guidance scale
@@ -358,10 +379,10 @@ def run_inference_2_2(
         )
         ref_noise_pred = noise_pred
         ref_latent = latents
-        ref_timestep = t_float
-        accum_dx = 0.0
-        accum_dt = 0.0
-        reuse_count = 0
+        ref_timestep = jnp.array(t_float, dtype=jnp.float32)
+        accum_dx = jnp.array(0.0, dtype=jnp.float32)
+        accum_dt = jnp.array(0.0, dtype=jnp.float32)
+        reuse_count = jnp.array(0, dtype=jnp.int32)
         latents, scheduler_state = scheduler.step(scheduler_state, noise_pred, t, latents).to_tuple()
         continue
 
@@ -375,12 +396,10 @@ def run_inference_2_2(
       score = alpha_x * accum_dx + alpha_t * accum_dt
 
       if score <= sen_epsilon and reuse_count < max_reuse:
-        # Cache hit: reuse previous output
         noise_pred = ref_noise_pred
         reuse_count += 1
         cache_count += 1
       else:
-        # Cache miss: full CFG forward pass
         latents_doubled = jnp.concatenate([latents] * 2)
         timestep = jnp.broadcast_to(t, bsz * 2)
         noise_pred, _, _ = transformer_forward_pass_full_cfg(
@@ -470,7 +489,7 @@ def run_inference_2_2(
     cached_noise_uncond = None
 
     for step in range(num_inference_steps):
-      t = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)[step]
+      t = timesteps[step]
       is_cache_step = step_is_cache[step]
 
       # Select transformer and guidance scale based on precomputed schedule
@@ -607,8 +626,6 @@ def low_noise_branch(operands):
     )
 
   if scan_diffusion_loop:
-    timesteps = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)
-
     scheduler_state = scheduler_state.replace(last_sample=jnp.zeros_like(latents), step_index=jnp.array(0, dtype=jnp.int32))
 
     def scan_body(carry, t):
@@ -657,7 +674,7 @@ def scan_body(carry, t):
       profiler = max_utils.Profiler(config)
       profiler.start()
 
-    t = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)[step]
+    t = timesteps[step]
 
     if step_uses_high[step]:
       graphdef, state, rest = (

src/maxdiffusion/pipelines/wan/wan_pipeline_i2v_2p1.py

@@ -213,19 +213,17 @@ def __call__(
         last_image,
     )
 
-    def _process_image_input(img_input, height, width, num_videos_per_prompt):
+    def _process_image_input(img_input, height, width):
       if img_input is None:
         return None
       tensor = self.video_processor.preprocess(img_input, height=height, width=width)
       jax_array = jnp.array(tensor.cpu().numpy())
       if jax_array.ndim == 3:
         jax_array = jax_array[None, ...]  # Add batch dimension
-      if num_videos_per_prompt > 1:
-        jax_array = jnp.repeat(jax_array, num_videos_per_prompt, axis=0)
       return jax_array
 
-    image_tensor = _process_image_input(image, height, width, effective_batch_size)
-    last_image_tensor = _process_image_input(last_image, height, width, effective_batch_size)
+    image_tensor = _process_image_input(image, height, width)
+    last_image_tensor = _process_image_input(last_image, height, width)
 
     if rng is None:
       rng = jax.random.key(self.config.seed)
@@ -352,6 +350,8 @@ def run_inference_2_1_i2v(
     image_embeds_combined = image_embeds
     condition_combined = condition
 
+  condition_combined = jnp.transpose(condition_combined, (0, 4, 1, 2, 3))
+
   transformer_obj = nnx.merge(graphdef, sharded_state, rest_of_state)
 
   # Compute RoPE once as it only depends on shape
@@ -373,10 +373,9 @@ def run_inference_2_1_i2v(
   )
 
   scan_diffusion_loop = getattr(config, "scan_diffusion_loop", False) if config else False
+  timesteps = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)
 
   if scan_diffusion_loop and not use_magcache:
-    timesteps = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)
-
     scheduler_state = scheduler_state.replace(last_sample=jnp.zeros_like(latents), step_index=jnp.array(0, dtype=jnp.int32))
 
     def scan_body(carry, t):
@@ -386,9 +385,9 @@ def scan_body(carry, t):
       if do_cfg:
         latents_input = jnp.concatenate([current_latents, current_latents], axis=0)
 
-      latent_model_input = jnp.concatenate([latents_input, condition_combined], axis=-1)
+      latents_input = jnp.transpose(latents_input, (0, 4, 1, 2, 3))
+      latent_model_input = jnp.concatenate([latents_input, condition_combined], axis=1)
       timestep = jnp.broadcast_to(t, latents_input.shape[0])
-      latent_model_input = jnp.transpose(latent_model_input, (0, 4, 1, 2, 3))
 
       outputs = transformer_forward_pass(
           graphdef,
@@ -429,7 +428,7 @@ def scan_body(carry, t):
       profiler = max_utils.Profiler(config)
       profiler.start()
 
-    t = jnp.array(scheduler_state.timesteps, dtype=jnp.int32)[step]
+    t = timesteps[step]
 
     skip_blocks = False
     if use_magcache and do_cfg:
@@ -446,9 +445,9 @@ def scan_body(carry, t):
     if do_cfg:
       latents_input = jnp.concatenate([latents, latents], axis=0)
 
-    latent_model_input = jnp.concatenate([latents_input, condition_combined], axis=-1)
+    latents_input = jnp.transpose(latents_input, (0, 4, 1, 2, 3))
+    latent_model_input = jnp.concatenate([latents_input, condition_combined], axis=1)
     timestep = jnp.broadcast_to(t, latents_input.shape[0])
-    latent_model_input = jnp.transpose(latent_model_input, (0, 4, 1, 2, 3))
 
     outputs = transformer_forward_pass(
         graphdef,