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

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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: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Reviewed-and-tested-by: Jay Patel <jaypatel@linux.ibm.com>
This commit is contained in:
Vlastimil Babka 2023-09-08 12:18:09 +02:00
parent 5886fc82b6
commit 90f055df11
1 changed files with 12 additions and 11 deletions
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23
mm/slub.c
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@ -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;