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Commit dd99e425 authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller
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udp: prefetch rmem_alloc in udp_queue_rcv_skb() 



On UDP packets processing, if the BH is the bottle-neck, it
always sees a cache miss while updating rmem_alloc; try to
avoid it prefetching the value as soon as we have the socket
available.

Performances under flood with multiple NIC rx queues used are
unaffected, but when a single NIC rx queue is in use, this
gives ~10% performance improvement.

Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent da2e9cf0

net/ipv4/udp.c

+1 −0
Original line number Diff line number Diff line
@@ -1949,6 +1949,7 @@ static int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb) 
		}

	}



	prefetch(&sk->sk_rmem_alloc);

	if (rcu_access_pointer(sk->sk_filter) &&

	    udp_lib_checksum_complete(skb))

			goto csum_error;