Non-blocking: Failure of suspension of any thread cannot cause failure of another thread.
- Lock-free: Guaranteed sys-wide progress
- Wait-free: Guaranteed per-thread progress
- atomic R/M/W pritives, like CAS
- Software transactional memory
simple DS: SRSW Ring FIFO
lock is not necessarily the mutex, but the possibility to lock the whole system up
Sequential Consistency: all threads agree on the order in which memory operations occurred, and that order is consistent with the order of operations in the program source code.
C++ atomic types guarantee sequential consistency.
If on multi-core, and no sequential consistency guarantee, mem reordering should be considered.
- Lightweight sync or fence instruction
- Full memory fence instruction
- Memory ops with acquire and release semantics