[Bugfix] Fix block size in block_table with PCP (#29094)

Signed-off-by: Livinfly <luojie3m@gmail.com>

vllm/v1/worker/block_table.py

@@ -84,7 +84,7 @@ class BlockTable:
             self.pcp_world_size = get_pcp_group().world_size
             self.pcp_rank = get_pcp_group().rank_in_group
         except AssertionError:
-            # DCP might not be initialized in testing
+            # PCP might not be initialized in testing
             self.pcp_world_size = 1
             self.pcp_rank = 0
         try:
@@ -268,6 +268,11 @@ class MultiGroupBlockTable:
         # (max_model_len//dcp_world_size) tokens in kvcache,
         # so the block_size which used for calc max_num_blocks_per_req
         # must be multiplied by dcp_world_size.
+        try:
+            pcp_world_size = get_pcp_group().world_size
+        except AssertionError:
+            # PCP might not be initialized in testing
+            pcp_world_size = 1
         try:
             dcp_world_size = get_dcp_group().world_size
         except AssertionError:
@@ -280,12 +285,14 @@ class MultiGroupBlockTable:
                 f"must match block_sizes length ({len(block_sizes)})"
             )
 
+        total_cp_world_size = dcp_world_size * pcp_world_size
+
         self.block_tables = [
             BlockTable(
                 block_size,
                 max_num_reqs,
                 max(
-                    cdiv(max_model_len, block_size * dcp_world_size),
+                    cdiv(max_model_len, block_size * total_cp_world_size),
                     1 + num_speculative_tokens,
                 ),
                 max_num_batched_tokens,