Optimise skb_attempt_defer_free() when run by the same CPU the skb was
allocated on. Instead of __kfree_skb() -> kmem_cache_free() we can
disable softirqs and put the buffer into cpu local caches.
CPU bound TCP ping pong style benchmarking (i.e. netbench) showed a 1%
throughput increase (392.2 -> 396.4 Krps). Cross checking with profiles,
the total CPU share of skb_attempt_defer_free() dropped by 0.6%. Note,
I'd expect the win doubled with rx only benchmarks, as the optimisation
is for the receive path, but the test spends >55% of CPU doing writes.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/a887463fb219d973ec5ad275e31194812571f1f5.1712711977.git.asml.silence@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
EXPORT_SYMBOL(__skb_ext_put);
#endif /* CONFIG_SKB_EXTENSIONS */
+static void kfree_skb_napi_cache(struct sk_buff *skb)
+{
+ /* if SKB is a clone, don't handle this case */
+ if (skb->fclone != SKB_FCLONE_UNAVAILABLE) {
+ __kfree_skb(skb);
+ return;
+ }
+
+ local_bh_disable();
+ __napi_kfree_skb(skb, SKB_DROP_REASON_NOT_SPECIFIED);
+ local_bh_enable();
+}
+
/**
* skb_attempt_defer_free - queue skb for remote freeing
* @skb: buffer
if (WARN_ON_ONCE(cpu >= nr_cpu_ids) ||
!cpu_online(cpu) ||
cpu == raw_smp_processor_id()) {
-nodefer: __kfree_skb(skb);
+nodefer: kfree_skb_napi_cache(skb);
return;
}