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Adjust kv_cache_size calculation based on local_attn_size #1008

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Merged
gushiqiao merged 1 commit into from
Apr 14, 2026
Merged

Adjust kv_cache_size calculation based on local_attn_size #1008

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6 changes: 5 additions & 1 deletion lightx2v/models/networks/wan/infer/lingbot_fast/transformer_infer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,11 @@ def _initialize_kv_cache(self, dtype, device):
return
kv_cache1 = []
ws = self._sp_world_size()
self.kv_cache_size = self._kv_size // ws
if self.local_attn_size != -1:
kv_cache_size = self.local_attn_size * self.frame_seq_length // ws
else:
kv_cache_size = self._kv_size // ws
self.kv_cache_size = kv_cache_size
Comment on lines +55 to +59
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@gemini-code-assist gemini-code-assist bot Apr 14, 2026

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medium

The current logic for calculating kv_cache_size ignores the max_attention_size override from the configuration (cfg_max in reinit_caches). If cfg_max is set to a value larger than the calculated local_attn_size * self.frame_seq_length, the attention mechanism will attempt to access indices outside the allocated KV cache, leading to a crash. Conversely, if cfg_max is smaller, memory is wasted. Since self.max_attention_size already correctly accounts for this override and sequence parallelism when local_attn_size != -1, it should be used to set the cache size to ensure consistency and robustness.

Suggested change
if self.local_attn_size != -1:
kv_cache_size = self.local_attn_size * self.frame_seq_length // ws
else:
kv_cache_size = self._kv_size // ws
self.kv_cache_size = kv_cache_size
if self.local_attn_size != -1:
self.kv_cache_size = self.max_attention_size
else:
self.kv_cache_size = self._kv_size // ws


n, d = self.num_heads, self.head_dim
if self.kv_quant_config is not None:
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