The defrag_ratio is used to set the threshold at which defragmentation should be attempted on a slab page. The allocation ratio is measured by the percentage of the available slots allocated. 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 slab defragmeentation runs. Reviewed-by: Rik van Riel Signed-off-by: Christoph Lameter Signed-off-by: Pekka Enberg Signed-off-by: Christoph Lameter --- include/linux/slub_def.h | 7 +++++++ mm/slub.c | 23 +++++++++++++++++++++++ 2 files changed, 30 insertions(+) Index: linux-2.6/include/linux/slub_def.h =================================================================== --- linux-2.6.orig/include/linux/slub_def.h 2008-07-31 12:20:16.000000000 -0500 +++ linux-2.6/include/linux/slub_def.h 2008-07-31 12:20:17.000000000 -0500 @@ -88,6 +88,13 @@ void (*ctor)(void *); int inuse; /* Offset to metadata */ int align; /* Alignment */ + int defrag_ratio; /* + * Ratio used to check the percentage of + * objects allocate in a slab page. + * If less than this ratio is allocated + * then reclaim attempts are made. + */ + 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 2008-07-31 12:20:16.000000000 -0500 +++ linux-2.6/mm/slub.c 2008-07-31 12:20:17.000000000 -0500 @@ -2299,6 +2299,7 @@ goto error; s->refcount = 1; + s->defrag_ratio = 30; #ifdef CONFIG_NUMA s->remote_node_defrag_ratio = 100; #endif @@ -4031,6 +4032,27 @@ } 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) +{ + unsigned long ratio; + int err; + + err = strict_strtoul(buf, 10, &ratio); + if (err) + return err; + + if (ratio < 100) + s->defrag_ratio = ratio; + return length; +} +SLAB_ATTR(defrag_ratio); + #ifdef CONFIG_NUMA static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf) { @@ -4138,6 +4160,7 @@ &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/