The defrag_ratio is used to set the threshold at which defragmentation should be run on a slabcache. The allocation ratio is measured in a percentage of the available slots. The percentage will be lower for slabs that are more fragmented. Add a defrag ratio field and set it to 30% by default. A limit of 30% specified that less than 3 out of 10 available slots for objects are in use before reclaim occurs. Reviewed-by: Rik van Riel Signed-off-by: Christoph Lameter --- include/linux/slub_def.h | 7 +++++++ mm/slub.c | 18 ++++++++++++++++++ 2 files changed, 25 insertions(+) Index: linux-2.6/include/linux/slub_def.h =================================================================== --- linux-2.6.orig/include/linux/slub_def.h 2007-11-06 12:36:28.000000000 -0800 +++ linux-2.6/include/linux/slub_def.h 2007-11-06 12:37:44.000000000 -0800 @@ -53,6 +53,13 @@ struct kmem_cache { void (*ctor)(struct kmem_cache *, void *); int inuse; /* Offset to metadata */ int align; /* Alignment */ + int defrag_ratio; /* + * objects/possible-objects limit. If we have + * less that the specified percentage of + * objects allocated then defrag passes + * will start to occur during reclaim. + */ + const char *name; /* Name (only for display!) */ struct list_head list; /* List of slab caches */ #ifdef CONFIG_SLUB_DEBUG Index: linux-2.6/mm/slub.c =================================================================== --- linux-2.6.orig/mm/slub.c 2007-11-06 12:37:25.000000000 -0800 +++ linux-2.6/mm/slub.c 2007-11-06 12:37:44.000000000 -0800 @@ -2363,6 +2363,7 @@ static int kmem_cache_open(struct kmem_c goto error; s->refcount = 1; + s->defrag_ratio = 30; #ifdef CONFIG_NUMA s->remote_node_defrag_ratio = 100; #endif @@ -4005,6 +4006,22 @@ static ssize_t free_calls_show(struct km } SLAB_ATTR_RO(free_calls); +static ssize_t defrag_ratio_show(struct kmem_cache *s, char *buf) +{ + return sprintf(buf, "%d\n", s->defrag_ratio); +} + +static ssize_t defrag_ratio_store(struct kmem_cache *s, + const char *buf, size_t length) +{ + int n = simple_strtoul(buf, NULL, 10); + + if (n < 100) + s->defrag_ratio = n; + return length; +} +SLAB_ATTR(defrag_ratio); + #ifdef CONFIG_NUMA static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf) { @@ -4047,6 +4064,7 @@ static struct attribute * slab_attrs[] = &shrink_attr.attr, &alloc_calls_attr.attr, &free_calls_attr.attr, + &defrag_ratio_attr.attr, #ifdef CONFIG_ZONE_DMA &cache_dma_attr.attr, #endif -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/