source: <커널코드2.6>/Documentation/mutex-design.txt
mutex 장점
- smaller structure: on x86, mutex is 16 bytes, semaphore is 20 bytes.
- tighter code: 25052 bytes of code saved
- faster: 2.4 times
- CONFIG_DEBUG_MUTEX 를 켜서 검사할 수있다.
* - only one task can hold the mutex at a time
* - only the owner can unlock the mutex