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Diffstat (limited to 'net/ipv4/tcp.c')
-rw-r--r--net/ipv4/tcp.c71
1 files changed, 57 insertions, 14 deletions
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 82de78603686..4475b3bb494d 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -285,6 +285,8 @@ int sysctl_tcp_fin_timeout __read_mostly = TCP_FIN_TIMEOUT;
int sysctl_tcp_min_tso_segs __read_mostly = 2;
+int sysctl_tcp_autocorking __read_mostly = 1;
+
struct percpu_counter tcp_orphan_count;
EXPORT_SYMBOL_GPL(tcp_orphan_count);
@@ -379,7 +381,7 @@ void tcp_init_sock(struct sock *sk)
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
- skb_queue_head_init(&tp->out_of_order_queue);
+ __skb_queue_head_init(&tp->out_of_order_queue);
tcp_init_xmit_timers(sk);
tcp_prequeue_init(tp);
INIT_LIST_HEAD(&tp->tsq_node);
@@ -619,19 +621,58 @@ static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
tp->snd_up = tp->write_seq;
}
-static inline void tcp_push(struct sock *sk, int flags, int mss_now,
- int nonagle)
+/* If a not yet filled skb is pushed, do not send it if
+ * we have data packets in Qdisc or NIC queues :
+ * Because TX completion will happen shortly, it gives a chance
+ * to coalesce future sendmsg() payload into this skb, without
+ * need for a timer, and with no latency trade off.
+ * As packets containing data payload have a bigger truesize
+ * than pure acks (dataless) packets, the last checks prevent
+ * autocorking if we only have an ACK in Qdisc/NIC queues,
+ * or if TX completion was delayed after we processed ACK packet.
+ */
+static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
+ int size_goal)
{
- if (tcp_send_head(sk)) {
- struct tcp_sock *tp = tcp_sk(sk);
+ return skb->len < size_goal &&
+ sysctl_tcp_autocorking &&
+ skb != tcp_write_queue_head(sk) &&
+ atomic_read(&sk->sk_wmem_alloc) > skb->truesize;
+}
+
+static void tcp_push(struct sock *sk, int flags, int mss_now,
+ int nonagle, int size_goal)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct sk_buff *skb;
- if (!(flags & MSG_MORE) || forced_push(tp))
- tcp_mark_push(tp, tcp_write_queue_tail(sk));
+ if (!tcp_send_head(sk))
+ return;
+
+ skb = tcp_write_queue_tail(sk);
+ if (!(flags & MSG_MORE) || forced_push(tp))
+ tcp_mark_push(tp, skb);
+
+ tcp_mark_urg(tp, flags);
+
+ if (tcp_should_autocork(sk, skb, size_goal)) {
- tcp_mark_urg(tp, flags);
- __tcp_push_pending_frames(sk, mss_now,
- (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
+ /* avoid atomic op if TSQ_THROTTLED bit is already set */
+ if (!test_bit(TSQ_THROTTLED, &tp->tsq_flags)) {
+ NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTOCORKING);
+ set_bit(TSQ_THROTTLED, &tp->tsq_flags);
+ }
+ /* It is possible TX completion already happened
+ * before we set TSQ_THROTTLED.
+ */
+ if (atomic_read(&sk->sk_wmem_alloc) > skb->truesize)
+ return;
}
+
+ if (flags & MSG_MORE)
+ nonagle = TCP_NAGLE_CORK;
+
+ __tcp_push_pending_frames(sk, mss_now, nonagle);
}
static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
@@ -934,7 +975,8 @@ new_segment:
wait_for_sndbuf:
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
wait_for_memory:
- tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
+ tcp_push(sk, flags & ~MSG_MORE, mss_now,
+ TCP_NAGLE_PUSH, size_goal);
if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
goto do_error;
@@ -944,7 +986,7 @@ wait_for_memory:
out:
if (copied && !(flags & MSG_SENDPAGE_NOTLAST))
- tcp_push(sk, flags, mss_now, tp->nonagle);
+ tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
return copied;
do_error:
@@ -1225,7 +1267,8 @@ wait_for_sndbuf:
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
wait_for_memory:
if (copied)
- tcp_push(sk, flags & ~MSG_MORE, mss_now, TCP_NAGLE_PUSH);
+ tcp_push(sk, flags & ~MSG_MORE, mss_now,
+ TCP_NAGLE_PUSH, size_goal);
if ((err = sk_stream_wait_memory(sk, &timeo)) != 0)
goto do_error;
@@ -1236,7 +1279,7 @@ wait_for_memory:
out:
if (copied)
- tcp_push(sk, flags, mss_now, tp->nonagle);
+ tcp_push(sk, flags, mss_now, tp->nonagle, size_goal);
release_sock(sk);
return copied + copied_syn;