slub: Make the order configurable for each slab cache
Makes /sys/kernel/slab/<slabname>/order writable. The allocation
order of a slab cache can then be changed dynamically during runtime.
This can be used to override the objects per slabs value establisheed
with the slub_min_objects setting that was manually specified or
calculated on bootup.
The changes of the slab order can occur while allocate_slab() runs.
Allocate slab needs the order and the number of slab objects that
are both changed by the change of order. Both are put into
a single word (struct kmem_cache_order_objects). They can then
be atomically updated and retrieved.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/mm/slub.c b/mm/slub.c
index de6f387..23a2683 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2218,7 +2218,7 @@
* calculate_sizes() determines the order and the distribution of data within
* a slab object.
*/
-static int calculate_sizes(struct kmem_cache *s)
+static int calculate_sizes(struct kmem_cache *s, int forced_order)
{
unsigned long flags = s->flags;
unsigned long size = s->objsize;
@@ -2307,7 +2307,10 @@
*/
size = ALIGN(size, align);
s->size = size;
- order = calculate_order(size);
+ if (forced_order >= 0)
+ order = forced_order;
+ else
+ order = calculate_order(size);
if (order < 0)
return 0;
@@ -2346,7 +2349,7 @@
s->align = align;
s->flags = kmem_cache_flags(size, flags, name, ctor);
- if (!calculate_sizes(s))
+ if (!calculate_sizes(s, -1))
goto error;
s->refcount = 1;
@@ -3833,11 +3836,23 @@
}
SLAB_ATTR_RO(objs_per_slab);
+static ssize_t order_store(struct kmem_cache *s,
+ const char *buf, size_t length)
+{
+ int order = simple_strtoul(buf, NULL, 10);
+
+ if (order > slub_max_order || order < slub_min_order)
+ return -EINVAL;
+
+ calculate_sizes(s, order);
+ return length;
+}
+
static ssize_t order_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", oo_order(s->oo));
}
-SLAB_ATTR_RO(order);
+SLAB_ATTR(order);
static ssize_t ctor_show(struct kmem_cache *s, char *buf)
{
@@ -3971,7 +3986,7 @@
s->flags &= ~SLAB_RED_ZONE;
if (buf[0] == '1')
s->flags |= SLAB_RED_ZONE;
- calculate_sizes(s);
+ calculate_sizes(s, -1);
return length;
}
SLAB_ATTR(red_zone);
@@ -3990,7 +4005,7 @@
s->flags &= ~SLAB_POISON;
if (buf[0] == '1')
s->flags |= SLAB_POISON;
- calculate_sizes(s);
+ calculate_sizes(s, -1);
return length;
}
SLAB_ATTR(poison);
@@ -4009,7 +4024,7 @@
s->flags &= ~SLAB_STORE_USER;
if (buf[0] == '1')
s->flags |= SLAB_STORE_USER;
- calculate_sizes(s);
+ calculate_sizes(s, -1);
return length;
}
SLAB_ATTR(store_user);