I always wondered if forking a giant processes (i.e., large memory footprint) to create a small processes caused a lot of needless memory to be allocated, but n

I always wondered if forking a giant processes (i.e., large memory footprint) to create a small processes caused a lot of needless memory to be allocated, but now I understand why its no big deal: For example, the fork/exec combo creates transient virtual memory usage spikes, which go away again almost immediately without ever breaking the copy on write status of most of the pages in the forked page tables. Thus if a large process forks off a smaller process, enormous physical memory demands threaten to happen (as far as overcommit is concerned), but never materialize.