The defrag_ratio is used to set the threshold when a slabcache should be defragmented. 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% that less than 3 out of 10 available slots for objects are in use. Signed-off-by: Christoph Lameter --- include/linux/slub_def.h | 7 +++++++ mm/slub.c | 18 ++++++++++++++++++ 2 files changed, 25 insertions(+), 0 deletions(-) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 5912b58..291881d 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -52,6 +52,13 @@ struct kmem_cache { void (*ctor)(void *, struct kmem_cache *, unsigned long); 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 diff --git a/mm/slub.c b/mm/slub.c index e63aba5..f95a760 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2200,6 +2200,7 @@ static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags, goto error; s->refcount = 1; + s->defrag_ratio = 30; #ifdef CONFIG_NUMA s->remote_node_defrag_ratio = 100; #endif @@ -3717,6 +3718,22 @@ static ssize_t free_calls_show(struct kmem_cache *s, char *buf) } 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) { @@ -3759,6 +3776,7 @@ 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 -- 1.5.2.4 -- - 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/