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

Christoph Lameter
2012-05-16T14:31:06Z

On Wed, 16 May 2012, Glauber Costa wrote:

> > 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 =)

These are local definitons only relevant for slab allocators using the
common slab code.

> > 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?

We could.

> 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)

Ok. Why would memcg need an additional state?

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

Sure. I thought there would only be special states before UP.

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

How so?

> > 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...

Yup.