Hi Pavel, >>>Well, you can have it as set of 0-1 "limits"... >> >>I have come up with a similar idea of regarding the ulimit >>value as a bitmask, and I think it may work. >>But it will be confusable for users to add the new concept of >>0-1 limitation into the traditional resouce limitation feature. >>Additionaly, this approach needs a modification of each shell >>command. >>What do you think about these demerits? > >>The /proc/<pid>/ approach doesn't have these demerits, and it >>has an advantage that users can change the bitmask of any process >>at anytime. > > Well... not sure if it is advantage.
For example, consider the following case: a process forks many children and system administrator wants to allow only one of these processes to dump shared memory. This is accomplished as follows: $ echo 1 > /proc/self/coremask $ ./some_program (fork children) $ echo 0 > /proc/<a child's pid>/coremask With the /proc/<pid>/ interface, we don't need to modify the user program. In contrast, with the ulimit or setrlimit interface, the administrator can't do it without modifying the user program to call setrlimit. This will not be preferred. > Semantics of ulimit inheritance > are well given, for example. How is this going to be inherited? The coremask setting is inherited in mm_init(), which is called once as an extention of do_fork(), do_execve() or compat_do_execve(). Inheritance is done by copying the bitmask from current->mm->coremask. However, if current->mm is NULL, the inherited bitmask is set to 0 (default value). Best regards, -- Hidehiro Kawai Hitachi, Ltd., Systems Development Laboratory - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
