Re: [RFC 0/4] reduce pid_namespace footprint when not configured

[ebiederm@xmission.com (Eric W. Biederman)]

Rasmus Villemoes <linux@rasmusvillemoes.dk> writes:

> A few suggestions for reducing the footprint of pid namespaces when
> CONFIG_PID_NS=n. The savings are admittedly not huge:
>
> $ scripts/bloat-o-meter /tmp/vmlinux.master vmlinux
> add/remove: 0/7 grow/shrink: 30/25 up/down: 368/-1032 (-664)

#ifdefs in C files.
More code to maintain.
Very minor savings.

I don't think it is worth the pain.  If anything I would prefer to
remove CONFIG_PID_NS.  The CONFIG_PID_NS ifdef really is about keeping
from exposing people to the feature tha don't use it more than it is
about size reduction.

Or do you have a case where this makes the difference between a usable
kernel and a kernel that is not?

Eric


> Rasmus Villemoes (4):
>   pid_namespace: remove ->level and ->parent for !CONFIG_PID_NS
>   pid_namespace: remove .kref field for !CONFIG_PID_NS
>   pid_namespace: make pid_nr_ns and pid_vnr static inlines for
>     !CONFIG_PID_NS
>   pid_namespace: disable_pid_allocation is unused for !CONFIG_PID_NS
>
>  include/linux/pid.h           | 11 +++++++++++
>  include/linux/pid_namespace.h | 20 ++++++++++++++++++++
>  kernel/acct.c                 |  4 ++--
>  kernel/pid.c                  | 24 +++++++++++++++---------
>  4 files changed, 48 insertions(+), 11 deletions(-)