Re: [RFC] SL[AUO]B common code 5/9] slabs: Common definition for boot state of the slab allocators

Glauber Costa
2012-05-16T08:21:35Z

On 05/15/2012 12:15 AM, Christoph Lameter wrote:
> ll allocators have some sort of support for the bootstrap status.
>
> Setup a common definition for the boot states and make all slab
> allocators use that definition.
>
> Signed-off-by: Christoph Lameter<cl@linux.com>

This is a good change.

> Index: linux-2.6/mm/slab.c
> ===================================================================
> --- linux-2.6.orig/mm/slab.c 2012-05-11 09:43:33.160436947 -0500
> +++ linux-2.6/mm/slab.c 2012-05-11 09:43:53.448436526 -0500
> @@ -87,6 +87,7 @@
> */
>
> #include <linux/slab.h>
> +#include "slab.h"

Why do we need a separate file for that?
I know some people do prefer it... I am not being one of them, just feel
forced to ask =)

> static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
> {
> - if (g_cpucache_up == FULL)
> + if (slab_state == FULL)
> return enable_cpucache(cachep, gfp);
>
> - if (g_cpucache_up == NONE) {
> + if (slab_state == DOWN) {

Can we avoid doing == tests here?

There are a couple of places where that test seems to be okay (I
remember 1 in the slub), but at least for the "FULL" test here, we
should be testing >= FULL.

Also, I don't like the name FULL too much, since I do intend to add a
new one soon (MEMCG, as you can see in my series)

Since we are using slab-specific states like PARTIAL_L3 here, maybe we
can use slub's like SYSFS here with no problem.

If we stick to >= and <= whenever needed, that should reflect a lot
better what the algorithm is really doing

> Index: linux-2.6/include/linux/slab.h
> ===================================================================
> --- linux-2.6.orig/include/linux/slab.h 2012-05-11 09:43:33.164436947 -0500
> +++ linux-2.6/include/linux/slab.h 2012-05-11 09:43:53.448436526 -0500
> @@ -117,10 +117,6 @@ int kmem_cache_shrink(struct kmem_cache
> void kmem_cache_free(struct kmem_cache *, void *);
> unsigned int kmem_cache_size(struct kmem_cache *);
>
> -/* Slab internal function */
> -struct kmem_cache *__kmem_cache_create(const char *, size_t, size_t,
> - unsigned long,
> - void (*)(void *));
> /*
> * Please use this macro to create slab caches. Simply specify the
> * name of the structure and maybe some flags that are listed above.
>

Should be in an earlier patch...