Hi Manish, Mulyadi, Yes I see it now, Thanks for your help. -Joel On Mon, Jan 11, 2010 at 6:22 AM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote: > On 1/11/10, Joel Fernandes <agnel.joel@xxxxxxxxx> wrote: >> Oh I'm sorry, if you were talking about copying of the address space >> information that can be avoided, that does not happen because it >> would've already been copied before exec() in the child gets a chance >> to execute.. the fork system call calls do_fork somewhere which calls >> copy_process which does this copying so it can't be avoided in any >> case. The book says copy-on-write itself has more overhead that is >> avoided with exec() in the child, but I'm trying to figure how. >> >> -Joel > > > Hi Joel... > > Manish is right. Please notice that he talked about "why do we do copy > on write (COW) if soon after child is forked, it quickly does exec()". > So yes, COW has overhead, but imagine if parent ran first. COW will be > triggered for parent address space, then child soon runs too. Then it > issues exec(). Clearly, this waste certain amout of memory which can > be fairly avoided if child runs first. > > Let me know if I say something not so obvious here.... > > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer and consultant > > blog: the-hydra.blogspot.com > training: mulyaditraining.blogspot.com > -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
