Re: [PATCH 0/8] core-small: Introduce CONFIG_CORE_SMALL from -tiny

[Andrew Morton <akpm@osdl.org>]

Matt Mackall <mpm@selenic.com> wrote:
>
> This set of patches introduces a new config option CONFIG_CORE_SMALL
> from the -tiny tree for small systems. This series should apply
> cleanly against 2.6.11-rc1-mm2.
> 
> When selected, it enables various tweaks to miscellaneous core data
> structures to shrink their size on small systems. While each tweak is
> fairly small, in aggregate they can save a substantial amount of
> memory.

You know what I'm going to ask ;)  How much memory?

I wish it didn't have "core" in the name.  A little misleading.

Did you think of making CONFIG_CORE_SMALL an integer which has values zero
or one?

Then you can lose all those ifdefs:

#define MAX_PROBE_HASH (255 - CONFIG_CORE_SMALL * 254)	/* dorky */

#define PID_MAX_DEFAULT (CONFIG_CORE_SMALL ? 0x1000 : 0x8000)
#define UIDHASH_BITS (CONFIG_CORE_SMALL ? 3 : 8)
#define FUTEX_HASHBITS (CONFIG_CORE_SMALL ? 4 : 8)
etc.

I think the ?: thing will work everywhere:

	#define XX 1
	char xx[XX ? 10 : 20];

even this works...