At least two is the best answer I can give without specifying a specific libc and architecture. Something to think about is that the binary size of libc is only

At least two is the best answer I can give without specifying a specific libc and architecture. Something to think about is that the binary size of libc is only half the story. Even if the executable portion of libc fits in a single page. A libc implementation has a lot of per thread and per process statics it holds onto. A good libc developer could actually put these into separate pages based on how often they change. In other words, if a static only is ever set once then coalesce it into a page with other statics that are only set once and are not process dependent. Why that's important: because of fork, when fork creates a new process it sets the parent processes pages read only and then preforms copy on write when they are modified. In theory you can share both the binary and some of the statics between all the processes.