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Fix kv cache, given resize will destroys the logical structure

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Haowei Zhang 2025-10-27 02:23:08 -07:00
parent c75fe54aa7
commit b062b422ac
1 changed files with 4 additions and 3 deletions
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nanochat/engine.py
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@ -135,9 +135,10 @@ class KVCache:
if t1 > self.kv_cache.size(4):
t_needed = t1 + 1024 # as much as we need plus buffer of 1024
t_needed = (t_needed + 1023) & ~1023 # then round up to the nearest multiple of 1024
current_shape = list(self.kv_cache.shape)
current_shape[4] = t_needed
self.kv_cache.resize_(current_shape)
additional_shape = list(self.kv_cache.shape)
additional_shape[4] = t_needed - self.kv_cache.size(4)
additional_cache = torch.empty(additional_shape, dtype=k.dtype, device=k.device)
self.kv_cache = torch.cat([self.kv_cache, additional_cache], dim=4).contiguous()
# Insert k, v into the cache
self.kv_cache[layer_idx, 0, :, :, t0:t1] = k
self.kv_cache[layer_idx, 1, :, :, t0:t1] = v