| Message ID | 20170425171541.3417-2-edumazet@google.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Tue, Apr 25, 2017 at 1:15 PM, Eric Dumazet <edumazet@google.com> wrote: > 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 <edumazet@google.com> Acked-by: Soheil Hassas Yeganeh <soheil@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 > Nice patchset. Thanks, Eric!
On Tue, Apr 25, 2017 at 1:15 PM, Eric Dumazet <edumazet@google.com> wrote: > 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 <edumazet@google.com> > --- This series is great! Thanks, Eric! Acked-by: Neal Cardwell <ncardwell@google.com> neal
On Tue, Apr 25, 2017 at 10:15 AM, Eric Dumazet <edumazet@google.com> wrote: > 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 <edumazet@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 */ Eric: would this new stamp cover outgoing packet as well in the future? in the patch series seem to cover only the incoming packets. > 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 >
On Tue, Apr 25, 2017 at 2:27 PM, Yuchung Cheng <ycheng@google.com> wrote: >> + struct skb_mstamp tcp_mstamp; /* most recent packet received/sent */ > Eric: would this new stamp cover outgoing packet as well in the > future? in the patch series seem to cover only the incoming packets. This is the plan yes : tp->lsndtime will also be replaced for a better TSO autodefer. When it happens, tp->tcp_mstamp will be updated once per write episode. And we'll remove a lot of skb_mstamp_get(&skb->skb_mstamp) calls all over the places.
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) {
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 <edumazet@google.com> --- include/linux/tcp.h | 1 + net/ipv4/tcp_input.c | 3 +++ 2 files changed, 4 insertions(+)