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Commit 06b285dc authored by Christoph Lameter's avatar Christoph Lameter Committed by Pekka Enberg
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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: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
parent 319d1e24

mm/slub.c

+22 −7
Original line number Diff line number Diff line
@@ -2218,7 +2218,7 @@ static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags) 
 * 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;
@@ -2307,6 +2307,9 @@ static int calculate_sizes(struct kmem_cache *s) 
	 */

	size = ALIGN(size, align);

	s->size = size;

	if (forced_order >= 0)

		order = forced_order;

	else

		order = calculate_order(size);



	if (order < 0)
@@ -2346,7 +2349,7 @@ static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags, 
	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 @@ static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf) 
}

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 @@ static ssize_t red_zone_store(struct kmem_cache *s, 
	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 @@ static ssize_t poison_store(struct kmem_cache *s, 
	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 @@ static ssize_t store_user_store(struct kmem_cache *s, 
	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);