Additional Tracing -for Perf Debugging

[kumaramit01]

💸 TL;DR

This PR adds a bunch more of tracing to debug performance bottleneck in Milvus. Expected trace for search
With all tracing enabled, a search request should show like this -We are seeing for non-failed queries search latencies > 1.5 sec

With a lot of time in schedule and segcore. The additional tracing would help us determine if the issue is with the

• MVCC timestamp filtering
• Pipeline setup (LocalPlanner + drivers)
• CGo overhead

0ms     → [Go Layer] Search request starts
         ...
CGo Boundary →
         async_search_cgo_entry
         before_future_async
         async_lambda_start
         before_span_start
         after_span_start
         SegCoreSearch span begins
         before_lazy_check_schema
         after_lazy_check_schema
         segment_search_start
         obtained_segment_lock_mutex
         before_check_search
         after_check_search
         before_create_visitor
         after_create_visitor
         visitor_before_plan_fragment
         visitor_before_query_context
         visitor_before_execute_task
         execute_task_before_create
         execute_task_after_create
         task_next_start
         before_local_planner
         after_local_planner
         before_driver_factory_loop
         after_driver_factory_loop
         before_create_drivers
         after_create_drivers
         before_driver_execution_loop
         execute_task_before_loop
         mvcc_node_start
         mvcc_before_bitmap_creation
         mvcc_before_mask_timestamps
         mvcc_after_mask_timestamps    ← MVCC filtering time
         mvcc_after_mask_delete        ← Delete filtering time
         filter_bits_node_start
         filter_bits_before_eval
         filter_bits_after_eval        ← Expression evaluation time
         execute_task_after_loop
         visitor_after_execute_task
         before_segment_search
         start_knowhere_index_search   ← Actual vector search
         finish_knowhere_index_search
         finish_searching_vector_index
         after_segment_search
         segment_search_end
         async_lambda_end
         SegCoreSearch span ends (138ms total)

📜 Details

Design Doc

Jira

🧪 Testing Steps / Validation

✅ Checks

• CI tests (if present) are passing
• Adheres to code style for repo
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