diff options
| -rw-r--r-- | mm/slub.c | 73 |
1 files changed, 36 insertions, 37 deletions
diff --git a/mm/slub.c b/mm/slub.c index f7940048138c..63d281dfacdb 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -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; @@ -4139,16 +4134,8 @@ 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; - /* - * Attempt to find best configuration for a slab. This - * works by first attempting to generate a layout with - * the best configuration and backing off gradually. - * - * First we increase the acceptable waste in a slab. Then - * we reduce the minimum objects required in a slab. - */ min_objects = slub_min_objects; if (!min_objects) { /* @@ -4160,40 +4147,46 @@ 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); - while (min_objects > 1) { - unsigned int fraction; - - fraction = 16; - while (fraction >= 4) { - order = calc_slab_order(size, min_objects, - slub_max_order, fraction); - if (order <= slub_max_order) - return order; - fraction /= 2; - } - min_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; /* - * We were unable to place multiple objects in a slab. Now - * lets see if we can place a single object there. + * Attempt to find best configuration for a slab. This works by first + * attempting to generate a layout with the best possible configuration + * and backing off gradually. + * + * We start with accepting at most 1/16 waste and try to find the + * smallest order from min_objects-derived/slub_min_order up to + * slub_max_order that will satisfy the constraint. Note that increasing + * the order can only result in same or less fractional waste, not more. + * + * If that fails, we increase the acceptable fraction of waste and try + * again. The last iteration with fraction of 1/2 would effectively + * accept any waste and give us the order determined by min_objects, as + * long as at least single object fits within slub_max_order. */ - order = calc_slab_order(size, 1, slub_max_order, 1); - if (order <= slub_max_order) - return order; + for (unsigned int fraction = 16; fraction > 1; fraction /= 2) { + order = calc_slab_order(size, min_order, slub_max_order, + fraction); + if (order <= slub_max_order) + return order; + } /* * Doh this slab cannot be placed using slub_max_order. */ - order = calc_slab_order(size, 1, MAX_ORDER, 1); + order = get_order(size); if (order <= MAX_ORDER) return order; return -ENOSYS; @@ -4711,6 +4704,9 @@ static int __init setup_slub_min_order(char *str) { get_option(&str, (int *)&slub_min_order); + if (slub_min_order > slub_max_order) + slub_max_order = slub_min_order; + return 1; } @@ -4721,6 +4717,9 @@ static int __init setup_slub_max_order(char *str) get_option(&str, (int *)&slub_max_order); slub_max_order = min_t(unsigned int, slub_max_order, MAX_ORDER); + if (slub_min_order > slub_max_order) + slub_min_order = slub_max_order; + return 1; } |