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

From: Eric W. Biederman
Date: Wed Sep 30 2015 - 17:10:13 EST

Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> 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?


> 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
> 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(-)
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