On 9/20/23 15:36, Feng Tang wrote:
> On Fri, Sep 08, 2023 at 10:53:07PM +0800, Vlastimil Babka wrote:
>> 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
>> calc_slab_order().
>
> Nit: here is to 'move ... to calculate_order()'?
Oops, right, fixed.
> I tried this patch series with normal boot on a desktop and one 2
> socket server: patch 2/4 doesn't change order of any slab, and patch
> 3/4 does make the slab order of big objects more consistent.
>
> Thanks for making the code much cleaner! And for the whole series,
>
> Reviewed-by: Feng Tang <feng.tang@xxxxxxxxx>
Thanks! Applied.
>
>> - 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@xxxxxxx>
>> ---
>> mm/slub.c | 19 +++++++++----------
>> 1 file changed, 9 insertions(+), 10 deletions(-)
>>
>> diff --git a/mm/slub.c b/mm/slub.c
>> index f04eb029d85a..1c91f72c7239 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;
>> @@ -4139,7 +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) {
>> @@ -4152,7 +4147,7 @@ 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);
>> @@ -4160,6 +4155,10 @@ static inline int calculate_order(unsigned int size)
>> max_objects = order_objects(slub_max_order, size);
>> min_objects = min(min_objects, max_objects);
>>
>> + min_order = max(slub_min_order, (unsigned int)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 and
>> @@ -4176,7 +4175,7 @@ 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;
>> --
>> 2.42.0
>>
>>
