net: rfs: add a jump label
RFS is not commonly used, so add a jump label to avoid some conditionals
in fast path.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 1ff5ea6..994f742 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -192,6 +192,7 @@
#ifdef CONFIG_RPS
#include <linux/static_key.h>
extern struct static_key rps_needed;
+extern struct static_key rfs_needed;
#endif
struct neighbour;
diff --git a/include/net/sock.h b/include/net/sock.h
index 1749e38..2729e77 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -913,17 +913,20 @@
static inline void sock_rps_record_flow(const struct sock *sk)
{
#ifdef CONFIG_RPS
- /* Reading sk->sk_rxhash might incur an expensive cache line miss.
- *
- * TCP_ESTABLISHED does cover almost all states where RFS
- * might be useful, and is cheaper [1] than testing :
- * IPv4: inet_sk(sk)->inet_daddr
- * IPv6: ipv6_addr_any(&sk->sk_v6_daddr)
- * OR an additional socket flag
- * [1] : sk_state and sk_prot are in the same cache line.
- */
- if (sk->sk_state == TCP_ESTABLISHED)
- sock_rps_record_flow_hash(sk->sk_rxhash);
+ if (static_key_false(&rfs_needed)) {
+ /* Reading sk->sk_rxhash might incur an expensive cache line
+ * miss.
+ *
+ * TCP_ESTABLISHED does cover almost all states where RFS
+ * might be useful, and is cheaper [1] than testing :
+ * IPv4: inet_sk(sk)->inet_daddr
+ * IPv6: ipv6_addr_any(&sk->sk_v6_daddr)
+ * OR an additional socket flag
+ * [1] : sk_state and sk_prot are in the same cache line.
+ */
+ if (sk->sk_state == TCP_ESTABLISHED)
+ sock_rps_record_flow_hash(sk->sk_rxhash);
+ }
#endif
}
diff --git a/net/core/dev.c b/net/core/dev.c
index bffb525..1d33ce0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3447,6 +3447,8 @@
struct static_key rps_needed __read_mostly;
EXPORT_SYMBOL(rps_needed);
+struct static_key rfs_needed __read_mostly;
+EXPORT_SYMBOL(rfs_needed);
static struct rps_dev_flow *
set_rps_cpu(struct net_device *dev, struct sk_buff *skb,
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 0df2aa6..2a46e40 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -79,10 +79,13 @@
if (sock_table != orig_sock_table) {
rcu_assign_pointer(rps_sock_flow_table, sock_table);
- if (sock_table)
+ if (sock_table) {
static_key_slow_inc(&rps_needed);
+ static_key_slow_inc(&rfs_needed);
+ }
if (orig_sock_table) {
static_key_slow_dec(&rps_needed);
+ static_key_slow_dec(&rfs_needed);
synchronize_rcu();
vfree(orig_sock_table);
}