fork in linux?

[yemista]

Does anyone know why linux uses calls to fork to create new processes? Whats the advantage
of that over just creating a new process data structure and filling out the information? this is how I intend to do it in a multi-process OS im working on for fun and learning, but would it be better to try to go ahead and use the fork method?

[Love4Boobies]

Most implementations of fork() create a new process with the same pages the parent process has; copies of these are only made on write. It's a nice technique to save memory because child processes use code and data from their parent process more often than you'd think and the overhead is so small (for creating a PCB and then replacing it) that there is more to gain.

[yemista]

But if you plan to only have processes be single, small user programs, its ok not to bother to fork? Ideally, my OS will consist of a shell that runs user programs from disk through a prompt.

[Love4Boobies]

It's okay either way. The fork() technique gives you better performance in some cases.