Re: [GIT PULL] printk for 5.10 (includes lockless ringbuffer)

From: Geert Uytterhoeven
Date: Wed Oct 14 2020 - 11:07:55 EST


Hi Rasmus,

On Wed, Oct 14, 2020 at 4:58 PM Rasmus Villemoes
<linux@xxxxxxxxxxxxxxxxxx> wrote:
> On 14/10/2020 16.16, Geert Uytterhoeven wrote:
> > On Mon, Oct 12, 2020 at 4:50 PM Petr Mladek <pmladek@xxxxxxxx> wrote:
> >> - Fully lockless ringbuffer implementation, including the support for
> >> continuous lines. It will allow to store and read messages in any
> >> situation wihtout the risk of deadlocks and without the need
> >> of temporary per-CPU buffers.
> >
> > linux-m68k-atari_defconfig$ bloat-o-meter vmlinux.old
> > vmlinux.lockless_ringbuffer
> > add/remove: 39/16 grow/shrink: 9/15 up/down: 214075/-4362 (209713)
> > Function old new delta
> > _printk_rb_static_infos - 180224 +180224
> > _printk_rb_static_descs - 24576 +24576
> > [...]
> >
> > Seriously?!? Or am I being misled by the tools?
> >
> > linux-m68k-atari_defconfig$ size vmlinux.old vmlinux.lockless_ringbuffer
> > text data bss dec hex filename
> > 3559108 941716 177772 4678596 4763c4 vmlinux.old
> > 3563922 1152496 175276 4891694 4aa42e vmlinux.lockless_ringbuffer
> >
> > Apparently not...
>
> Hm, that's quite a lot. And the only reason the buffers don't live
> entirely in .bss is because a few of their entries have non-zero
> initializers.

Even if this would live in BSS, it would still consume 200 KiB of RAM.
Or am I missing something?

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds