Hi, Samuel Thibault wrote: >> Then must process-shared semaphores and mutexes be implemented in >> shared memory? or it's completely through IPCs? > > Note that posix mutexes are always shared between processus through > shared memory anyway (the application is responsible for sharing the > memory). That can be used for fast locking (through atomics etc) and > reverting to ports can be done only in the contention case. > > For semaphores, sem_init() behaves the same way. sem_open() is different > in that it doesn't requires shared memory, but I'd advise to just > automatically set up a shared memory segment and just work the same. > > Anyway, deciding between shared memory or pure IPC is not really an > issue. I believe the more difficult part is how to make process > actually perform IPCs securely. It can probably be useful to check how > shm was implemented. Do you mean shm device in Linux or in Xen?
Zheng Da
