We want to use precise timestamps in TCP stack, but we do not
want to call possibly expensive kernel time services too often.
tp->tcp_mstamp is guaranteed to be updated once per incoming packet.
We will use it in the following patches, removing specific
skb_mstamp_get() calls, and removing ack_time from
struct tcp_sacktag_state.
Signed-off-by: Eric Dumazet <eduma...@google.com>
---
include/linux/tcp.h | 1 +
net/ipv4/tcp_input.c | 3 +++
2 files changed, 4 insertions(+)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index
cbe5b602a2d349fdeb1e878305f37b4da1e6cc86..99a22f44c32e1587a6bf4835b65c7a4314807aa8
100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -240,6 +240,7 @@ struct tcp_sock {
u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */
/* RTT measurement */
+ struct skb_mstamp tcp_mstamp; /* most recent packet received/sent */
u32 srtt_us; /* smoothed round trip time << 3 in usecs */
u32 mdev_us; /* medium deviation */
u32 mdev_max_us; /* maximal mdev for the last rtt period */
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index
5af2f04f885914491a7116c20056b3d2188d2d7d..bd18c65df4a9d9c2b66d8005f2cc4ff468140a73
100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5362,6 +5362,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff
*skb,
{
struct tcp_sock *tp = tcp_sk(sk);
+ skb_mstamp_get(&tp->tcp_mstamp);
if (unlikely(!sk->sk_rx_dst))
inet_csk(sk)->icsk_af_ops->sk_rx_dst_set(sk, skb);
/*
@@ -5922,6 +5923,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff
*skb)
case TCP_SYN_SENT:
tp->rx_opt.saw_tstamp = 0;
+ skb_mstamp_get(&tp->tcp_mstamp);
queued = tcp_rcv_synsent_state_process(sk, skb, th);
if (queued >= 0)
return queued;
@@ -5933,6 +5935,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff
*skb)
return 0;
}
+ skb_mstamp_get(&tp->tcp_mstamp);
tp->rx_opt.saw_tstamp = 0;
req = tp->fastopen_rsk;
if (req) {
--
2.13.0.rc0.306.g87b477812d-goog
