Read Copy Update (RCU)
Even RwLock needs to update the state in synchronization variable, which undergoes the same performance issue: lock contention.
Read-Copy-Update Overview
- Goal: very fast read
- Restricted update
- Writer computes a new version
- Publish the new version with single atomic write
- Readers may see old or new version
- Integrated with scheduler
- Grace Period
- When all readers lose the reference to old version, then gc.
