This patch introduces a new socket option SO_SYMMETRIC_QUEUES that can be used
to enable symmetric tx and rx queues on a socket.
This option is specifically useful for epoll based multi threaded workloads
where each thread handles packets received on a single RX queue . In this model,
we have noticed that it helps to send the packets on the same TX queue
corresponding to the queue-pair associated with the RX queue specifically when
busy poll is enabled with epoll().
Two new fields are added to struct sock_common to cache the last rx ifindex and
the rx queue in the receive path of an SKB. __netdev_pick_tx() returns the
cached
rx queue when this option is enabled and the TX is happening on the same device.
Signed-off-by: Sridhar Samudrala <sridhar.samudr...@intel.com>
---
include/net/request_sock.h | 1 +
include/net/sock.h | 17 +++++++++++++++++
include/uapi/asm-generic/socket.h | 2 ++
net/core/dev.c | 8 +++++++-
net/core/sock.c | 10 ++++++++++
net/ipv4/tcp_input.c | 1 +
net/ipv4/tcp_ipv4.c | 1 +
net/ipv4/tcp_minisocks.c | 1 +
8 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 23e2205..c3bc12e 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -100,6 +100,7 @@ static inline struct sock *req_to_sk(struct request_sock
*req)
req_to_sk(req)->sk_prot = sk_listener->sk_prot;
sk_node_init(&req_to_sk(req)->sk_node);
sk_tx_queue_clear(req_to_sk(req));
+ req_to_sk(req)->sk_symmetric_queues = sk_listener->sk_symmetric_queues;
req->saved_syn = NULL;
refcount_set(&req->rsk_refcnt, 0);
diff --git a/include/net/sock.h b/include/net/sock.h
index 03a3625..3421809 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -138,11 +138,14 @@ void SOCK_DEBUG(const struct sock *sk, const char *msg,
...)
* @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_rx_queue_mapping: rx queue number for this connection
+ * @skc_rx_ifindex: rx ifindex 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
+ * @skc_symmetric_queues: symmetric tx/rx queues
*
* This is the minimal network layer representation of sockets, the header
* for struct sock and struct inet_timewait_sock.
@@ -177,6 +180,7 @@ struct sock_common {
unsigned char skc_reuseport:1;
unsigned char skc_ipv6only:1;
unsigned char skc_net_refcnt:1;
+ unsigned char skc_symmetric_queues:1;
int skc_bound_dev_if;
union {
struct hlist_node skc_bind_node;
@@ -214,6 +218,8 @@ struct sock_common {
struct hlist_nulls_node skc_nulls_node;
};
int skc_tx_queue_mapping;
+ int skc_rx_queue_mapping;
+ int skc_rx_ifindex;
union {
int skc_incoming_cpu;
u32 skc_rcv_wnd;
@@ -324,6 +330,8 @@ struct sock {
#define sk_nulls_node __sk_common.skc_nulls_node
#define sk_refcnt __sk_common.skc_refcnt
#define sk_tx_queue_mapping __sk_common.skc_tx_queue_mapping
+#define sk_rx_queue_mapping __sk_common.skc_rx_queue_mapping
+#define sk_rx_ifindex __sk_common.skc_rx_ifindex
#define sk_dontcopy_begin __sk_common.skc_dontcopy_begin
#define sk_dontcopy_end __sk_common.skc_dontcopy_end
@@ -340,6 +348,7 @@ struct sock {
#define sk_reuseport __sk_common.skc_reuseport
#define sk_ipv6only __sk_common.skc_ipv6only
#define sk_net_refcnt __sk_common.skc_net_refcnt
+#define sk_symmetric_queues __sk_common.skc_symmetric_queues
#define sk_bound_dev_if __sk_common.skc_bound_dev_if
#define sk_bind_node __sk_common.skc_bind_node
#define sk_prot __sk_common.skc_prot
@@ -1676,6 +1685,14 @@ static inline int sk_tx_queue_get(const struct sock *sk)
return sk ? sk->sk_tx_queue_mapping : -1;
}
+static inline void sk_mark_rx_queue(struct sock *sk, struct sk_buff *skb)
+{
+ if (sk->sk_symmetric_queues) {
+ sk->sk_rx_ifindex = skb->skb_iif;
+ sk->sk_rx_queue_mapping = skb_get_rx_queue(skb);
+ }
+}
+
static inline void sk_set_socket(struct sock *sk, struct socket *sock)
{
sk_tx_queue_clear(sk);
diff --git a/include/uapi/asm-generic/socket.h
b/include/uapi/asm-generic/socket.h
index e47c9e4..f6b416e 100644
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -106,4 +106,6 @@
#define SO_ZEROCOPY 60
+#define SO_SYMMETRIC_QUEUES 61
+
#endif /* __ASM_GENERIC_SOCKET_H */
diff --git a/net/core/dev.c b/net/core/dev.c
index 270b547..d96cda8 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3322,7 +3322,13 @@ static u16 __netdev_pick_tx(struct net_device *dev,
struct sk_buff *skb)
if (queue_index < 0 || skb->ooo_okay ||
queue_index >= dev->real_num_tx_queues) {
- int new_index = get_xps_queue(dev, skb);
+ int new_index = -1;
+
+ if (sk && sk->sk_symmetric_queues && dev->ifindex ==
sk->sk_rx_ifindex)
+ new_index = sk->sk_rx_queue_mapping;
+
+ if (new_index < 0 || new_index >= dev->real_num_tx_queues)
+ new_index = get_xps_queue(dev, skb);
if (new_index < 0)
new_index = skb_tx_hash(dev, skb);
diff --git a/net/core/sock.c b/net/core/sock.c
index 9b7b6bb..3876cce 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1059,6 +1059,10 @@ int sock_setsockopt(struct socket *sock, int level, int
optname,
sock_valbool_flag(sk, SOCK_ZEROCOPY, valbool);
break;
+ case SO_SYMMETRIC_QUEUES:
+ sk->sk_symmetric_queues = valbool;
+ break;
+
default:
ret = -ENOPROTOOPT;
break;
@@ -1391,6 +1395,10 @@ int sock_getsockopt(struct socket *sock, int level, int
optname,
v.val = sock_flag(sk, SOCK_ZEROCOPY);
break;
+ case SO_SYMMETRIC_QUEUES:
+ v.val = sk->sk_symmetric_queues;
+ break;
+
default:
/* We implement the SO_SNDLOWAT etc to not be settable
* (1003.1g 7).
@@ -2738,6 +2746,8 @@ 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;
+ sk->sk_rx_ifindex = -1;
+ sk->sk_rx_queue_mapping = -1;
/*
* Before updating sk_refcnt, we must commit prior changes to memory
* (Documentation/RCU/rculist_nulls.txt for details)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index c5d7656..12381e0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6356,6 +6356,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
tcp_rsk(req)->snt_isn = isn;
tcp_rsk(req)->txhash = net_tx_rndhash();
tcp_openreq_init_rwin(req, sk, dst);
+ sk_mark_rx_queue(req_to_sk(req), skb);
if (!want_cookie) {
tcp_reqsk_record_syn(sk, req, skb);
fastopen_sk = tcp_try_fastopen(sk, skb, req, &foc);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a63486a..82f9af4 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1450,6 +1450,7 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
sock_rps_save_rxhash(sk, skb);
sk_mark_napi_id(sk, skb);
+ sk_mark_rx_queue(sk, skb);
if (dst) {
if (inet_sk(sk)->rx_dst_ifindex != skb->skb_iif ||
!dst->ops->check(dst, 0)) {
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 188a6f3..2b5efd5 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -809,6 +809,7 @@ int tcp_child_process(struct sock *parent, struct sock
*child,
/* record NAPI ID of child */
sk_mark_napi_id(child, skb);
+ sk_mark_rx_queue(child, skb);
tcp_segs_in(tcp_sk(child), skb);
if (!sock_owned_by_user(child)) {
--
1.8.3.1
