On Thu, 27 Nov 2008, Eric Dumazet wrote:

with slub_min_objects=45 :

# cat /sys/kernel/slab/filp/order
2
# time ./socket8
real    0m1.652s
user    0m0.694s
sys     0m12.367s

That may be a good value. How many processor do you have? Look at
calculate_order() in mm/slub.c:

   if (!min_objects)
                min_objects = 4 * (fls(nr_cpu_ids) + 1);

We couild increase the scaling factor there or start
with a mininum of 20 objects?


Try

	min_objects = 20 + 4 * (fls(nr_cpu_ids) + 1);

I would say slub_min_objects=45 is the optimal value on 32bit arches to
get acceptable performance on this workload (order=2 for filp kmem_cache)

Note : SLAB here is disastrous, but you already knew that :)

Its good though to have examples where the queue management gets in the
way of performance.