On Fri, Nov 11, 2011 at 10:07 PM, Christoph Lameter <cl@xxxxxxxxx> wrote:
> get_freelist retrieves free objects from the page freelist (put there by remote
> frees) or deactivates a slab page if no more objects are available.
>
> Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
This is a also a nice cleanup. Any reason I shouldn't apply this?
>
>
> ---
> mm/slub.c | 57 ++++++++++++++++++++++++++++++++-------------------------
> 1 file changed, 32 insertions(+), 25 deletions(-)
>
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c 2011-11-09 11:10:55.671388657 -0600
> +++ linux-2.6/mm/slub.c 2011-11-09 11:11:13.471490305 -0600
> @@ -2110,6 +2110,37 @@ static inline void *new_slab_objects(str
> }
>
> /*
> + * Check the page->freelist of a page and either transfer the freelist to the per cpu freelist
> + * or deactivate the page.
> + *
> + * The page is still frozen if the return value is not NULL.
> + *
> + * If this function returns NULL then the page has been unfrozen.
> + */
> +static inline void *get_freelist(struct kmem_cache *s, struct page *page)
> +{
> + struct page new;
> + unsigned long counters;
> + void *freelist;
> +
> + do {
> + freelist = page->freelist;
> + counters = page->counters;
> + new.counters = counters;
> + VM_BUG_ON(!new.frozen);
> +
> + new.inuse = page->objects;
> + new.frozen = freelist != NULL;
> +
> + } while (!cmpxchg_double_slab(s, page,
> + freelist, counters,
> + NULL, new.counters,
> + "get_freelist"));
> +
> + return freelist;
> +}
> +
> +/*
> * Slow path. The lockless freelist is empty or we need to perform
> * debugging duties.
> *
> @@ -2130,8 +2161,6 @@ static void *__slab_alloc(struct kmem_ca
> {
> void **object;
> unsigned long flags;
> - struct page new;
> - unsigned long counters;
>
> local_irq_save(flags);
> #ifdef CONFIG_PREEMPT
> @@ -2156,29 +2185,7 @@ redo:
>
> stat(s, ALLOC_SLOWPATH);
>
> - do {
> - object = c->page->freelist;
> - counters = c->page->counters;
> - new.counters = counters;
> - VM_BUG_ON(!new.frozen);
> -
> - /*
> - * If there is no object left then we use this loop to
> - * deactivate the slab which is simple since no objects
> - * are left in the slab and therefore we do not need to
> - * put the page back onto the partial list.
> - *
> - * If there are objects left then we retrieve them
> - * and use them to refill the per cpu queue.
> - */
> -
> - new.inuse = c->page->objects;
> - new.frozen = object != NULL;
> -
> - } while (!__cmpxchg_double_slab(s, c->page,
> - object, counters,
> - NULL, new.counters,
> - "__slab_alloc"));
> + object = get_freelist(s, c->page);
>
> if (!object) {
> c->page = NULL;
>
> --
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