title: can I over run the tmpfs size
body: <p>I'm trying to use /dev/shm tmpfs for writing my files. The default is half of the physical RAM  without swap. When I write something beyond the size of this mount, it gives an error "No space left on the disk".</p>
  
  <p>My question is, shouldn't it be using swap space rather than erroring out? Is there a way I can let my application use up more than what is allocated for tmpfs, maybe through an option?</p>
  
  <p>What happens if one of my processes is running and has used up almost all of the space in /dev/shm and I have another process running (outside of /dev/shm) which also uses more than 50% of RAM space? Which one is swapped out? </p>
  
  <p>For example, let's say my total physical memory is 40 GB and tmpfs is 20GB. One of the processes is using /dev/shm and is about 20GB. Now there is another process running which takes around 30GB. Which one of the processes will swap out? Or it cannot be determined?</p>