[patch 07/23] SLUB: Add defrag_ratio field and sysfs support.

Christoph Lameter
2007-11-07T01:14:50Z

[-- Attachment #1: 0004-slab_defrag_add_defrag_ratio.patch --]
[-- Type: text/plain, Size: 2585 bytes --]

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 <riel@redhat.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
---
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

--