On Wed, Dec 15, 2010 at 3:33 PM, Dave Hylands <dhylands@xxxxxxxxx> wrote: > Hi guys, > > On Wed, Dec 15, 2010 at 10:50 AM, Enrico Granata <egranata@xxxxxxxx> wrote: >> I believe his question actually sounds like: why does Linux need two system >> calls to start running a new program? Wouldn't it be simpler to do this the >> way Win32 does it: a CreateProcess() system call that actually loads a NEW >> program in NEW process? > > So fork is actually the heavyweight variant. It copies the page tables > of the calling process. > > If you know that the fork will be followed by an exec, then you're > better off to use the lightweight version of fork, called vfork, which > does not copy the page tables of the calling process. > > Also keep in mind that it's perfectly legal to call fork without calling exec. > > And, fork and vfork are really just front-ends for clone which is the > function that deals with all of the variants... > > -- > Dave Hylands > Shuswap, BC, Canada > http://www.DaveHylands.com/ Thanks Dave, So == if (vfork()) execve(...) == would be ultra-lightweight at the fork level because not even the page tables would be copied. I didn't know that. Seems extremely useful for huge programs that need to spin-off a little task. Always something new to learn. Greg -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
