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[Bugfix][TPU] Fix KV cache size calculation #5860

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Merged
merged 1 commit into from
Jun 26, 2024
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[Bugfix][TPU] Fix KV cache size calculation #5860

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13 changes: 7 additions & 6 deletions vllm/worker/tpu_worker.py
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Original file line number Diff line number Diff line change
Expand Up @@ -118,14 +118,15 @@ def determine_num_available_blocks(self) -> Tuple[int, int]:
xm.wait_device_ops()

m = xm.get_memory_info(self.device)
program_size = 1024 * 1024 * 1024 # 1GB
free_bytes = max(m["bytes_limit"] - m["bytes_used"] - program_size, 0)
kv_cache_bytes = int(free_bytes *
self.cache_config.gpu_memory_utilization)
kv_cache_dtype_btyes = get_dtype_size(self.cache_dtype)
total_memory_size = m["bytes_limit"]
usable_memory_size = int(total_memory_size *
self.cache_config.gpu_memory_utilization)
profiled = m["bytes_used"] # Weights + intermediate activations.
kv_cache_bytes = max(usable_memory_size - profiled, 0)
dtype_btyes = get_dtype_size(self.cache_dtype)
block_size = self.cache_config.block_size
num_tpu_blocks = (kv_cache_bytes //
(kv_cache_dtype_btyes * block_size * num_layers * 2 *
(dtype_btyes * block_size * num_layers * 2 *
head_size * num_kv_heads))
num_tpu_blocks = (num_tpu_blocks // 8) * 8 # Round down to 8.
return num_tpu_blocks, 0
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