On Fri, May 21, 2010 at 2:47 AM, Alexander Duyck
<alexander.h.duyck@xxxxxxxxx> wrote:
> This patch is meant to improve the performance of SLUB by moving the local
> kmem_cache_node lock into it's own cacheline separate from kmem_cache.
> This is accomplished by simply removing the local_node when NUMA is enabled.
>
> On my system with 2 nodes I saw around a 5% performance increase w/
> hackbench times dropping from 6.2 seconds to 5.9 seconds on average. I
> suspect the performance gain would increase as the number of nodes
> increases, but I do not have the data to currently back that up.
>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
Yanmin, does this fix the hackbench regression for you?
> ---
>
> include/linux/slub_def.h | 11 ++++-------
> mm/slub.c | 33 +++++++++++----------------------
> 2 files changed, 15 insertions(+), 29 deletions(-)
>
> diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
> index 0249d41..e6217bb 100644
> --- a/include/linux/slub_def.h
> +++ b/include/linux/slub_def.h
> @@ -52,7 +52,7 @@ struct kmem_cache_node {
> atomic_long_t total_objects;
> struct list_head full;
> #endif
> -};
> +} ____cacheline_internodealigned_in_smp;
>
> /*
> * Word size structure that can be atomically updated or read and that
> @@ -75,12 +75,6 @@ struct kmem_cache {
> int offset; /* Free pointer offset. */
> struct kmem_cache_order_objects oo;
>
> - /*
> - * Avoid an extra cache line for UP, SMP and for the node local to
> - * struct kmem_cache.
> - */
> - struct kmem_cache_node local_node;
> -
> /* Allocation and freeing of slabs */
> struct kmem_cache_order_objects max;
> struct kmem_cache_order_objects min;
> @@ -102,6 +96,9 @@ struct kmem_cache {
> */
> int remote_node_defrag_ratio;
> struct kmem_cache_node *node[MAX_NUMNODES];
> +#else
> + /* Avoid an extra cache line for UP */
> + struct kmem_cache_node local_node;
> #endif
> };
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 461314b..8af03de 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2141,7 +2141,7 @@ static void free_kmem_cache_nodes(struct kmem_cache *s)
>
> for_each_node_state(node, N_NORMAL_MEMORY) {
> struct kmem_cache_node *n = s->node[node];
> - if (n && n != &s->local_node)
> + if (n)
> kmem_cache_free(kmalloc_caches, n);
> s->node[node] = NULL;
> }
> @@ -2150,33 +2150,22 @@ static void free_kmem_cache_nodes(struct kmem_cache *s)
> static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
> {
> int node;
> - int local_node;
> -
> - if (slab_state >= UP && (s < kmalloc_caches ||
> - s >= kmalloc_caches + KMALLOC_CACHES))
> - local_node = page_to_nid(virt_to_page(s));
> - else
> - local_node = 0;
>
> for_each_node_state(node, N_NORMAL_MEMORY) {
> struct kmem_cache_node *n;
>
> - if (local_node == node)
> - n = &s->local_node;
> - else {
> - if (slab_state == DOWN) {
> - early_kmem_cache_node_alloc(gfpflags, node);
> - continue;
> - }
> - n = kmem_cache_alloc_node(kmalloc_caches,
> - gfpflags, node);
> -
> - if (!n) {
> - free_kmem_cache_nodes(s);
> - return 0;
> - }
> + if (slab_state == DOWN) {
> + early_kmem_cache_node_alloc(gfpflags, node);
> + continue;
> + }
> + n = kmem_cache_alloc_node(kmalloc_caches,
> + gfpflags, node);
>
> + if (!n) {
> + free_kmem_cache_nodes(s);
> + return 0;
> }
> +
> s->node[node] = n;
> init_kmem_cache_node(n, s);
> }
>
> --
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