net: align sk_refcnt on 128 bytes boundary
sk->sk_refcnt is dirtied for every TCP/UDP incoming packet.
This is a performance issue if multiple cpus hit a common socket,
or multiple sockets are chained due to SO_REUSEPORT.
By moving sk_refcnt 8 bytes further, first 128 bytes of sockets
are mostly read. As they contain the lookup keys, this has
a considerable performance impact, as cpus can cache them.
These 8 bytes are not wasted, we use them as a place holder
for various fields, depending on the socket type.
Tested:
SYN flood hitting a 16 RX queues NIC.
TCP listener using 16 sockets and SO_REUSEPORT
and SO_INCOMING_CPU for proper siloing.
Could process 6.0 Mpps SYN instead of 4.2 Mpps
Kernel profile looked like :
11.68% [kernel] [k] sha_transform
6.51% [kernel] [k] __inet_lookup_listener
5.07% [kernel] [k] __inet_lookup_established
4.15% [kernel] [k] memcpy_erms
3.46% [kernel] [k] ipt_do_table
2.74% [kernel] [k] fib_table_lookup
2.54% [kernel] [k] tcp_make_synack
2.34% [kernel] [k] tcp_conn_request
2.05% [kernel] [k] __netif_receive_skb_core
2.03% [kernel] [k] kmem_cache_alloc
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 cf54739..6571240 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -150,6 +150,9 @@
* @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_flags: place holder for sk_flags
+ * %SO_LINGER (l_onoff), %SO_BROADCAST, %SO_KEEPALIVE,
+ * %SO_OOBINLINE settings, %SO_TIMESTAMPING settings
* @skc_incoming_cpu: record/match cpu processing incoming packets
* @skc_refcnt: reference count
*
@@ -201,6 +204,16 @@
atomic64_t skc_cookie;
+ /* following fields are padding to force
+ * offset(struct sock, sk_refcnt) == 128 on 64bit arches
+ * assuming IPV6 is enabled. We use this padding differently
+ * for different kind of 'sockets'
+ */
+ union {
+ unsigned long skc_flags;
+ struct sock *skc_listener; /* request_sock */
+ struct inet_timewait_death_row *skc_tw_dr; /* inet_timewait_sock */
+ };
/*
* fields between dontcopy_begin/dontcopy_end
* are not copied in sock_copy()
@@ -246,8 +259,6 @@
* @sk_pacing_rate: Pacing rate (if supported by transport/packet scheduler)
* @sk_max_pacing_rate: Maximum pacing rate (%SO_MAX_PACING_RATE)
* @sk_sndbuf: size of send buffer in bytes
- * @sk_flags: %SO_LINGER (l_onoff), %SO_BROADCAST, %SO_KEEPALIVE,
- * %SO_OOBINLINE settings, %SO_TIMESTAMPING settings
* @sk_no_check_tx: %SO_NO_CHECK setting, set checksum in TX packets
* @sk_no_check_rx: allow zero checksum in RX packets
* @sk_route_caps: route capabilities (e.g. %NETIF_F_TSO)
@@ -334,6 +345,7 @@
#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
+#define sk_flags __sk_common.skc_flags
socket_lock_t sk_lock;
struct sk_buff_head sk_receive_queue;
@@ -371,7 +383,6 @@
#ifdef CONFIG_XFRM
struct xfrm_policy *sk_policy[2];
#endif
- unsigned long sk_flags;
struct dst_entry *sk_rx_dst;
struct dst_entry __rcu *sk_dst_cache;
spinlock_t sk_dst_lock;