net: SO_INCOMING_CPU setsockopt() support

SO_INCOMING_CPU as added in commit 2c8c56e15df3 was a getsockopt() command
to fetch incoming cpu handling a particular TCP flow after accept()

This commits adds setsockopt() support and extends SO_REUSEPORT selection
logic : If a TCP listener or UDP socket has this option set, a packet is
delivered to this socket only if CPU handling the packet matches the specified
one.

This allows to build very efficient TCP servers, using one listener per
RX queue, as the associated TCP listener should only accept flows handled
in softirq by the same cpu.
This provides optimal NUMA behavior and keep cpu caches hot.

Note that __inet_lookup_listener() still has to iterate over the list of
all listeners. Following patch puts sk_refcnt in a different cache line
to let this iteration hit only shared and read mostly cache lines.

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

diff --git a/include/net/sock.h b/include/net/sock.h
index 9322caf..cf54739 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -150,6 +150,7 @@ typedef __u64 __bitwise __addrpair;
  *     @skc_node: main hash linkage for various protocol lookup tables
  *     @skc_nulls_node: main hash linkage for TCP/UDP/UDP-Lite protocol
  *     @skc_tx_queue_mapping: tx queue number for this connection
+ *     @skc_incoming_cpu: record/match cpu processing incoming packets
  *     @skc_refcnt: reference count
  *
  *     This is the minimal network layer representation of sockets, the header
@@ -212,6 +213,8 @@ struct sock_common {
                struct hlist_nulls_node skc_nulls_node;
        };
        int                     skc_tx_queue_mapping;
+       int                     skc_incoming_cpu;
+
        atomic_t                skc_refcnt;
        /* private: */
        int                     skc_dontcopy_end[0];
@@ -274,7 +277,6 @@ struct cg_proto;
   *    @sk_rcvtimeo: %SO_RCVTIMEO setting
   *    @sk_sndtimeo: %SO_SNDTIMEO setting
   *    @sk_rxhash: flow hash received from netif layer
-  *    @sk_incoming_cpu: record cpu processing incoming packets
   *    @sk_txhash: computed flow hash for use on transmit
   *    @sk_filter: socket filtering instructions
   *    @sk_timer: sock cleanup timer
@@ -331,6 +333,7 @@ struct sock {
 #define sk_v6_daddr            __sk_common.skc_v6_daddr
 #define sk_v6_rcv_saddr        __sk_common.skc_v6_rcv_saddr
 #define sk_cookie              __sk_common.skc_cookie
+#define sk_incoming_cpu                __sk_common.skc_incoming_cpu
 
        socket_lock_t           sk_lock;
        struct sk_buff_head     sk_receive_queue;
@@ -353,11 +356,6 @@ struct sock {
 #ifdef CONFIG_RPS
        __u32                   sk_rxhash;
 #endif
-       u16                     sk_incoming_cpu;
-       /* 16bit hole
-        * Warned : sk_incoming_cpu can be set from softirq,
-        * Do not use this hole without fully understanding possible issues.
-        */
 
        __u32                   sk_txhash;
 #ifdef CONFIG_NET_RX_BUSY_POLL

diff --git a/net/core/sock.c b/net/core/sock.c
index 3395777..dcc7d62 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -988,6 +988,10 @@ set_rcvbuf:
                                         sk->sk_max_pacing_rate);
                break;
 
+       case SO_INCOMING_CPU:
+               sk->sk_incoming_cpu = val;
+               break;
+
        default:
                ret = -ENOPROTOOPT;
                break;
@@ -2379,6 +2383,7 @@ void sock_init_data(struct socket *sock, struct sock *sk)
 
        sk->sk_max_pacing_rate = ~0U;
        sk->sk_pacing_rate = ~0U;
+       sk->sk_incoming_cpu = -1;
        /*
         * Before updating sk_refcnt, we must commit prior changes to memory
         * (Documentation/RCU/rculist_nulls.txt for details)

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index bed8886..08643a3 100644 (file)
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -185,6 +185,8 @@ static inline int compute_score(struct sock *sk, struct net *net,
                                return -1;
                        score += 4;
                }
+               if (sk->sk_incoming_cpu == raw_smp_processor_id())
+                       score++;
        }
        return score;
 }

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e1fc129..24ec14f 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -375,7 +375,8 @@ static inline int compute_score(struct sock *sk, struct net *net,
                        return -1;
                score += 4;
        }
-
+       if (sk->sk_incoming_cpu == raw_smp_processor_id())
+               score++;
        return score;
 }
 
@@ -419,6 +420,9 @@ static inline int compute_score2(struct sock *sk, struct net *net,
                score += 4;
        }
 
+       if (sk->sk_incoming_cpu == raw_smp_processor_id())
+               score++;
+
        return score;
 }
 

diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 6ac8dad..21ace5a 100644 (file)
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -114,6 +114,8 @@ static inline int compute_score(struct sock *sk, struct net *net,
                                return -1;
                        score++;
                }
+               if (sk->sk_incoming_cpu == raw_smp_processor_id())
+                       score++;
        }
        return score;
 }

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 0aba654..01bcb49 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -182,10 +182,12 @@ static inline int compute_score(struct sock *sk, struct net *net,
                score++;
        }
 
+       if (sk->sk_incoming_cpu == raw_smp_processor_id())
+               score++;
+
        return score;
 }
 
-#define SCORE2_MAX (1 + 1 + 1)
 static inline int compute_score2(struct sock *sk, struct net *net,
                                 const struct in6_addr *saddr, __be16 sport,
                                 const struct in6_addr *daddr,
@@ -223,6 +225,9 @@ static inline int compute_score2(struct sock *sk, struct net *net,
                score++;
        }
 
+       if (sk->sk_incoming_cpu == raw_smp_processor_id())
+               score++;
+
        return score;
 }
 
@@ -251,8 +256,7 @@ begin:
                                hash = udp6_ehashfn(net, daddr, hnum,
                                                    saddr, sport);
                                matches = 1;
-                       } else if (score == SCORE2_MAX)
-                               goto exact_match;
+                       }
                } else if (score == badness && reuseport) {
                        matches++;
                        if (reciprocal_scale(hash, matches) == 0)
@@ -269,7 +273,6 @@ begin:
                goto begin;
 
        if (result) {
-exact_match:
                if (unlikely(!atomic_inc_not_zero_hint(&result->sk_refcnt, 2)))
                        result = NULL;
                else if (unlikely(compute_score2(result, net, saddr, sport,