On 14/02/12 11:15, Michael Schnell wrote: > > System 5 named semaphores (sem_open() and friends) are designed to work > system wide and (AFAI remember) don’t need any userspace memory resources. sem_open() is _not_ part of System V semaphores, it's part of POSIX semaphores and part of nptl. It uses futex internally. Henry