From 93d5f41937be8d2d9b89a7501462d2a8fc6354df Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Thu, 9 Aug 2007 07:51:45 -0700 Subject: [PATCH] SLUB: Add defrag_ratio field and sysfs support. The defrag_ratio is used to set the threshold at which defragmentation should be run on a slabcache. The allocation ratio is measured in the percentage of the available slots allocated. 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 slab defragmeentation runs. 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-2.6.24-rc2-mm1/include/linux/slub_def.h =================================================================== --- linux-2.6.24-rc2-mm1.orig/include/linux/slub_def.h 2007-11-14 11:10:03.796012330 -0800 +++ linux-2.6.24-rc2-mm1/include/linux/slub_def.h 2007-11-14 12:06:05.330593714 -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-2.6.24-rc2-mm1/mm/slub.c =================================================================== --- linux-2.6.24-rc2-mm1.orig/mm/slub.c 2007-11-14 11:10:22.236011521 -0800 +++ linux-2.6.24-rc2-mm1/mm/slub.c 2007-11-14 12:06:05.338343172 -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 @@ -4009,6 +4010,22 @@ 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) { @@ -4051,6 +4068,7 @@ 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