reduce lock_sys.wait_mutex contention by using spinloop construct
- wait_mutex plays an important role when the workload involves conflicting transactions.
- On a heavily contented system with increasing scalability
quite possible that the majority of the transactions may have to wait
before acquiring resources.
- This causes a lot of contention of wait_mutex but most of this
the contention is short-lived that tend to suggest the use of spin loop
to avoid giving up compute core that in turn will involve os-scheduler with additional latency.
- Idea has shown promising results with performance improving up to 70-100% for write workload.