title: Posix shared memory vs mapped files
body: <p>Having learnt a bit about the subject, can anyone tell, what is the real difference between POSIX shared memory (shm_open) and POSIX mapped files (mmap)?</p>
  
  <p>Both seems to use the /dev/tmpfs subsystem, rather then older IPC mechanism.</p>
  
  <p>So is there any advantage of using mmap file over shared memory?</p>
  
  <p>Thanks.</p>