On Fri, Nov 11, 2011 at 10:07 PM, Christoph Lameter <cl@xxxxxxxxx> wrote:
> The kmem_cache_cpu object pointed to by c will become
> volatile with the lockless patches later so extract
> the c->page pointer at certain times.
>
> Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
I don't know what GCC does these days but this sort of thing used to
generate better asm in mm/slab.c. So it might be worth it to merge
this.
> ---
> mm/slub.c | 17 ++++++++++-------
> 1 file changed, 10 insertions(+), 7 deletions(-)
>
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c 2011-11-09 11:11:25.881561697 -0600
> +++ linux-2.6/mm/slub.c 2011-11-09 11:11:32.231598204 -0600
> @@ -2160,6 +2160,7 @@ static void *__slab_alloc(struct kmem_ca
> unsigned long addr, struct kmem_cache_cpu *c)
> {
> void *freelist;
> + struct page *page;
> unsigned long flags;
>
> local_irq_save(flags);
> @@ -2172,13 +2173,14 @@ static void *__slab_alloc(struct kmem_ca
> c = this_cpu_ptr(s->cpu_slab);
> #endif
>
> - if (!c->page)
> + page = c->page;
> + if (!page)
> goto new_slab;
> redo:
>
> if (unlikely(!node_match(c, node))) {
> stat(s, ALLOC_NODE_MISMATCH);
> - deactivate_slab(s, c->page, c->freelist);
> + deactivate_slab(s, page, c->freelist);
> c->page = NULL;
> c->freelist = NULL;
> goto new_slab;
> @@ -2186,7 +2188,7 @@ redo:
>
> stat(s, ALLOC_SLOWPATH);
>
> - freelist = get_freelist(s, c->page);
> + freelist = get_freelist(s, page);
>
> if (unlikely(!freelist)) {
> c->page = NULL;
> @@ -2210,8 +2212,8 @@ load_freelist:
> new_slab:
>
> if (c->partial) {
> - c->page = c->partial;
> - c->partial = c->page->next;
> + page = c->page = c->partial;
> + c->partial = page->next;
> stat(s, CPU_PARTIAL_ALLOC);
> c->freelist = NULL;
> goto redo;
> @@ -2231,13 +2233,14 @@ new_slab:
> return NULL;
> }
>
> + page = c->page;
> if (likely(!kmem_cache_debug(s)))
> goto load_freelist;
>
> /* Only entered in the debug case */
> - if (!alloc_debug_processing(s, c->page, freelist, addr))
> + if (!alloc_debug_processing(s, page, freelist, addr))
> goto new_slab; /* Slab failed checks. Next slab needed */
> - deactivate_slab(s, c->page, get_freepointer(s, freelist));
> + deactivate_slab(s, page, get_freepointer(s, freelist));
>
> c->page = NULL;
> c->freelist = NULL;
>
> --
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