Re: Kernel 2.6 size increase

From: "Randy.Dunlap" <rddunlap@osdl.org>
To: "David S. Miller" <davem@redhat.com>
Cc: root@chaos.analogic.com, bernie@develer.com,
	uclinux-dev@uclinux.org, linux-kernel@vger.kernel.org
Subject: Re: Kernel 2.6 size increase
Date: Wed, 23 Jul 2003 14:47:19 -0700	[thread overview]
Message-ID: <20030723144719.103adc19.rddunlap@osdl.org> (raw)
In-Reply-To: <20030723130712.6ac59b56.davem@redhat.com>

On Wed, 23 Jul 2003 13:07:12 -0700 "David S. Miller" <davem@redhat.com> wrote:

| On Wed, 23 Jul 2003 15:14:22 -0400 (EDT)
| "Richard B. Johnson" <root@chaos.analogic.com> wrote:
| 
| > On Wed, 23 Jul 2003, Bernardo Innocenti wrote:
| > It looks like a lot of data may have been initialized in the
| > newer kernel, i.e. int barf = 0; or struct vomit = {0,}.
| > If they just declared the static data, it would end up in
| > .bss which is allocated at run-time (and zeroed) and is
| > not in the kernel image.
| 
| GCC 3.3 and later do this automatically.
| 
| It's weird, since we killed TONS of explicit zero initializers during
| 2.5.x, you'd be pressed to find many examples like the one you
| mention.
| 
| Another thing is that the define_per_cpu() stuff eliminated many huge
| [NR_CPUS] arrays.  But this probably doesn't apply to his kernel
| unless he built is with SMP enabled.

Yes, lots were already killed off, but there are also several
kernel-janitor patches to remove many more static 0 inits.
They can be found at
  http://developer.osdl.org/ogasawara/kj-patches/uninit_static/
and I'll be trying to have them merged, although I don't know
how well they will be accepted.

--
~Randy