Re: [pull request] getting rid of __cpuinit

From: Sam Ravnborg
Date: Sat Oct 25 2008 - 03:58:28 EST


On Fri, Oct 24, 2008 at 02:20:56PM -0700, Arjan van de Ven wrote:
> Hi Linus,
>
> this is one of those pull requests for which the best timing is likely at the
> end of the merge window due to touching a large number of files in a trivial way.
> In fact, 6 of the 8 patches were done via regexps:
>
> find -name "*.c" | xargs sed -i "s/^__cpuinit //g"
> find arch/ -name "*.h" | xargs sed -i "s/ __cpuinit//g"
> find -name "*.c" | xargs sed -i "s/ __cpuinit$//g"
> find -name "*.c" | xargs sed -i "s/ __cpuinitdata//g"
> find -name "*.c" | xargs sed -i "s/ __cpuexit / /g"
> find -name "*.c" | xargs sed -i "s/ __cpuinit / /g"
>
> (I suppose asking for a "git sed" is too much to do...)
>
> The point of this series is to get rid of __cpuinit. (I'll be working on other __XXXXinit after this)
> __cpuinit is a NOOP for CONFIG_HOTPLUG_CPU, which on for just about anybody in practice
> (in fact I had to disable 6 common options to even be ABLE to turn it off for size testing)
> and all distros also ship with it enabled.
>
> Yet it's a rather error prone construct since the rules of this sort of __XXXXinit thing are
> rather complex and convoluted.. better to just get rid of it entirely.
>
> As for the code size effect, after I spent a bunch of time cursing and trying to find out
> how to disable HOTPLUG_CPU, I managed to get an x86-64 build that actually shows how much space
> we ACTUALLY save with all the __cpuinit's in the tree... it's less than 2Kb. That is, if you manage
> to turn it actually off.
>
> text data bss dec hex filename
> 4618096 1358684 848588 6825368 682598 vmlinux.before
> 4619965 1356908 848716 6825589 682675 vmlinux.after

The interesting number here is the size of the cpuinit/cpuexit sections.
cpuinit sections are discarded after init and cpuexit sections are discarded
if you do not use modules.

Can you share these numbers with us?

Sam
--
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/