This patchset is the first real use-case for kmem_cache bulk _free_.
The use of bulk _alloc_ is NOT included in this patchset. The full use
have previously been posted here [1].
The bulk free side have the largest benefit for the network stack
use-case, because network stack is hitting the kmem_cache/SLUB
slowpath when freeing SKBs, due to the amount of outstanding SKBs.
This is solved by using the new API kmem_cache_free_bulk().
Introduce new API napi_consume_skb(), that hides/handles bulk freeing
for the caller. The drivers simply need to use this call when freeing
SKBs in NAPI context, e.g. replacing their calles to dev_kfree_skb() /
dev_consume_skb_any().