Re: [PATCH] nextfd(2)

[KOSAKI Motohiro]

(4/4/12 10:49 AM), Ulrich Drepper wrote:
> On Wed, Apr 4, 2012 at 13:07, KOSAKI Motohiro<kosaki.motohiro@xxxxxxxxx>  wrote:
> > Umm... I'm sorry. I haven't catch why OOM is related topic. Could you please
> > elaborate more?
>
> With fork you always have some copy-on-write (and worse for
> overcommit) just to then execute exec.  With a real spawn
> implementation you wouldn't have that.  A big problem if you, for
> instance, have to spawn a small helper from a gigantic process.

Ah, ok. I agree posix_spawn() has a chance to aim more momemory efficiency
than fork-exec. But in this purpose, vfork may be enough useful and be widely
accepted from userland folks.

Example, some daemon has a following patten,
 1. fork
 2. change /proc/<pid>/oom_adj
 3. exec

That's said, when adding linux specific knob, we need to add new posix_spawn flags
if we really need (or want) to replaces all userland. this seems very hard and doubtful
worth to me.

Ahh, note. I'm not against to implement posix_spawn() into the kernel. I only argue spawn()
can solve closefrom issue.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/