af_packet: Avoid cache line dirtying
While doing multiple captures, I found af_packet was dirtying cache line
containing its prot_hook.
This slow down machines where several cpus are necessary to handle capture
traffic, as each prot_hook is traversed for each packet coming in or out
the host.
This patches moves "struct packet_type prot_hook" to the end of
packet_sock, and uses a ____cacheline_aligned_in_smp to make sure
this remains shared by all cpus.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index bf3a295..dac775e 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -188,7 +188,6 @@
struct packet_ring_buffer tx_ring;
int copy_thresh;
#endif
- struct packet_type prot_hook;
spinlock_t bind_lock;
struct mutex pg_vec_lock;
unsigned int running:1, /* prot_hook is attached*/
@@ -204,6 +203,7 @@
unsigned int tp_reserve;
unsigned int tp_loss:1;
#endif
+ struct packet_type prot_hook ____cacheline_aligned_in_smp;
};
struct packet_skb_cb {