[TPU][V1] Fix padding recompilation when max-num-batched-tokens is not even (#16726)

Signed-off-by: NickLucche <[email protected]>

Author: NickLucche

tests/v1/tpu/worker/test_tpu_model_runner.py

@@ -294,11 +294,19 @@ def test_update_states_request_unscheduled(model_runner):
 
 
 def test_get_paddings():
+    # Bucketed padding
     min_token_size, max_token_size, padding_gap = 16, 512, 64
     expected_paddings = [16, 32, 64, 128, 192, 256, 320, 384, 448, 512]
+    actual_paddings = _get_token_paddings(min_token_size, max_token_size,
+                                          padding_gap)
+
+    # Bucketed padding with max_token_size not a power of two.
+    max_token_size = 317
+    expected_paddings = [16, 32, 64, 128, 192, 256, 320]
     actual_paddings = _get_token_paddings(min_token_size, max_token_size,
                                           padding_gap)
     assert actual_paddings == expected_paddings
+
     # Exponential padding.
     max_token_size, padding_gap = 1024, 0
     expected_paddings = [16, 32, 64, 128, 256, 512, 1024]

vllm/v1/worker/tpu_model_runner.py

@@ -128,10 +128,16 @@ def __init__(
         self.block_size = cache_config.block_size
         self.max_model_len = model_config.max_model_len
         self.max_num_blocks_per_req = cdiv(self.max_model_len, self.block_size)
-        self.max_num_tokens = scheduler_config.max_num_batched_tokens
         # InputBatch needs to work with sampling tensors greater than padding
         # to avoid dynamic shapes. Also, avoid suboptimal alignment.
         self.max_num_reqs = max(scheduler_config.max_num_seqs, MIN_NUM_SEQS)
+        self.num_tokens_paddings = _get_token_paddings(
+            min_token_size=16,
+            max_token_size=scheduler_config.max_num_batched_tokens,
+            padding_gap=envs.VLLM_TPU_BUCKET_PADDING_GAP)
+        # In case `max_num_tokens < max(num_tokens_paddings)` use the actual
+        # padded max value to pre-allocate data structures and pre-compile.
+        self.max_num_tokens = self.num_tokens_paddings[-1]
 
         # Model-related.
         self.num_attn_layers = model_config.get_num_layers_by_block_type(
@@ -211,10 +217,6 @@ def __init__(
         # Range tensor with values [0 .. self.max_num_tokens - 1].
         # Used to initialize positions / context_lens / seq_lens
         self.arange_np = np.arange(self.max_num_tokens, dtype=np.int32)
-        self.num_tokens_paddings = _get_token_paddings(
-            min_token_size=16,
-            max_token_size=self.max_num_tokens,
-            padding_gap=envs.VLLM_TPU_BUCKET_PADDING_GAP)
         self.num_reqs_paddings = _get_req_paddings(
             min_req_size=MIN_NUM_SEQS, max_req_size=self.max_num_reqs)
 

vllm/v1/worker/tpu_worker.py

@@ -156,8 +156,8 @@ def determine_available_memory(self) -> int:
             self.vllm_config.compilation_config.static_forward_context,
             runner_kv_caches)
 
-        self.model_runner._dummy_run(
-            self.scheduler_config.max_num_batched_tokens)
+        # `max_num_tokens >= max_num_batched_tokens` due to padding.
+        self.model_runner._dummy_run(self.model_runner.max_num_tokens)
 
         # Synchronize before measuring the memory usage.
         xm.wait_device_ops()