net: shrink struct softnet_data

flow_limit in struct softnet_data is only read from local cpu
and can be moved to fill a hole, reducing softnet_data size by
64 bytes on x86_64

While we are at it, move output_queue, output_queue_tailp and
completion_queue, so that rx / tx paths touch a single cache line.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c85e065122460e9f077bcb6788018be38e1d7ddf..5ed05bd764dcf3699afdd9a7b17600246de22d1d 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2329,10 +2329,7 @@ extern int netdev_flow_limit_table_len;
  * Incoming packets are placed on per-cpu queues
  */
 struct softnet_data {
-       struct Qdisc            *output_queue;
-       struct Qdisc            **output_queue_tailp;
        struct list_head        poll_list;
-       struct sk_buff          *completion_queue;
        struct sk_buff_head     process_queue;
 
        /* stats */
@@ -2340,10 +2337,17 @@ struct softnet_data {
        unsigned int            time_squeeze;
        unsigned int            cpu_collision;
        unsigned int            received_rps;
-
 #ifdef CONFIG_RPS
        struct softnet_data     *rps_ipi_list;
+#endif
+#ifdef CONFIG_NET_FLOW_LIMIT
+       struct sd_flow_limit __rcu *flow_limit;
+#endif
+       struct Qdisc            *output_queue;
+       struct Qdisc            **output_queue_tailp;
+       struct sk_buff          *completion_queue;
 
+#ifdef CONFIG_RPS
        /* Elements below can be accessed between CPUs for RPS */
        struct call_single_data csd ____cacheline_aligned_in_smp;
        struct softnet_data     *rps_ipi_next;
@@ -2355,9 +2359,6 @@ struct softnet_data {
        struct sk_buff_head     input_pkt_queue;
        struct napi_struct      backlog;
 
-#ifdef CONFIG_NET_FLOW_LIMIT
-       struct sd_flow_limit __rcu *flow_limit;
-#endif
 };
 
 static inline void input_queue_head_incr(struct softnet_data *sd)