Commit 90f055df authored by Vlastimil Babka's avatar Vlastimil Babka
Browse files

mm/slub: refactor calculate_order() and calc_slab_order() 



After the previous cleanups, we can now move some code from
calc_slab_order() to calculate_order() so it's executed just once, and
do some more cleanups.

- move the min_order and MAX_OBJS_PER_PAGE evaluation to
  calculate_order().

- change calc_slab_order() parameter min_objects to min_order

Also make MAX_OBJS_PER_PAGE check more robust by considering also
min_objects in addition to slub_min_order. Otherwise this is not a
functional change.

Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarFeng Tang <feng.tang@intel.com>
Reviewed-and-tested-by: default avatarJay Patel <jaypatel@linux.ibm.com>
parent 5886fc82

mm/slub.c

+12 −11
Original line number Diff line number Diff line
@@ -4110,17 +4110,12 @@ static unsigned int slub_min_objects; 
 * the smallest order which will fit the object.

 */

static inline unsigned int calc_slab_order(unsigned int size,

		unsigned int min_objects, unsigned int max_order,

		unsigned int min_order, unsigned int max_order,

		unsigned int fract_leftover)

{

	unsigned int min_order = slub_min_order;

	unsigned int order;



	if (order_objects(min_order, size) > MAX_OBJS_PER_PAGE)

		return get_order(size * MAX_OBJS_PER_PAGE) - 1;



	for (order = max(min_order, (unsigned int)get_order(min_objects * size));

			order <= max_order; order++) {

	for (order = min_order; order <= max_order; order++) {



		unsigned int slab_size = (unsigned int)PAGE_SIZE << order;

		unsigned int rem;
@@ -4139,7 +4134,7 @@ static inline int calculate_order(unsigned int size) 
	unsigned int order;

	unsigned int min_objects;

	unsigned int max_objects;

	unsigned int nr_cpus;

	unsigned int min_order;



	min_objects = slub_min_objects;

	if (!min_objects) {
@@ -4152,14 +4147,20 @@ static inline int calculate_order(unsigned int size) 
		 * order on systems that appear larger than they are, and too

		 * low order on systems that appear smaller than they are.

		 */

		nr_cpus = num_present_cpus();

		unsigned int nr_cpus = num_present_cpus();

		if (nr_cpus <= 1)

			nr_cpus = nr_cpu_ids;

		min_objects = 4 * (fls(nr_cpus) + 1);

	}

	max_objects = order_objects(slub_max_order, size);

	/* min_objects can't be 0 because get_order(0) is undefined */

	max_objects = max(order_objects(slub_max_order, size), 1U);

	min_objects = min(min_objects, max_objects);



	min_order = max_t(unsigned int, slub_min_order,

			  get_order(min_objects * size));

	if (order_objects(min_order, size) > MAX_OBJS_PER_PAGE)

		return get_order(size * MAX_OBJS_PER_PAGE) - 1;



	/*

	 * Attempt to find best configuration for a slab. This works by first

	 * attempting to generate a layout with the best possible configuration
@@ -4176,7 +4177,7 @@ static inline int calculate_order(unsigned int size) 
	 * long as at least single object fits within slub_max_order.

	 */

	for (unsigned int fraction = 16; fraction > 1; fraction /= 2) {

		order = calc_slab_order(size, min_objects, slub_max_order,

		order = calc_slab_order(size, min_order, slub_max_order,

					fraction);

		if (order <= slub_max_order)

			return order;