Hello, Please consider the following two suggestions for adjusting the vfork() man page. In the "Linux Description" section it should be mentioned that vfork() does not suspend all the threads in the parent process and only suspends the thread issuing the call to vfork(). The wording is misleading and I misunderstood the semantics for a long time, thinking that all threads would be suspended. Had to test it to determine the actual effect for certain. In our case suspending all threads for even a few microseconds is unacceptable. Also, it is important to note that the clone(CLONE_VFORK|CLONE_VM) call invoked by vfork() makes a separate copy of all process resources except the address space. While this is implied by the statement "the vfork() function has the same effect as fork(2)," this is easily overlooked by someone who works with various UNIXs where this is most definitely not the case. This matters for situations like ours where a process with a huge address space, real-time priority and root privileges must occasionally spawn scripts that should run at user priority with user privileges. Using fork() is expensive due to the cost of replicating very large page tables and vfork() is an excellent alternative. But the subtle difference between Solaris/AIX and Linux caused us to unnecessarily disable the code that lowers priority and surrenders root permission before issuing the exec() call to run scripts. Regards -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
