On Mon, Jul 30, 2012 at 01:53:03PM +0300, Konstantin Belousov wrote: > On Mon, Jul 30, 2012 at 12:24:08PM +0200, Jilles Tjoelker wrote: > > People sometimes use system() from large address spaces where it would > > improve performance greatly to use vfork() instead of fork().
> > A simple approach is to change fork() to vfork(), although I have not > > tried this. It seems safe enough to use sigaction and sigprocmask system > > calls in the vforked process. > > Alternatively, we can have posix_spawn() do the vfork() with signal > > changes. This avoids possible whining from compilers and static > > analyzers about using vfork() in system.c. However, I do not like the > > tricky code for signals and that it adds lines of code. > > This is lightly tested. > It is interesting to note that for some time our vfork(2) no longer > stops the whole forked process (parent), only the forking thread is > waiting for the child exit or exec. I am not sure is this point > important for system(3), but determined code can notice the difference > from the fork->vfork switch. Neither fork nor vfork call thread_single(SINGLE_BOUNDARY), so this is not a difference. Thread singling may be noticeable from a failing execve() (but only in the process doing execve()) and in the rare case of rfork() without RFPROC. -- Jilles Tjoelker _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
