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tcp: use tp->tcp_mstamp in output path

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Idea is to later convert tp->tcp_mstamp to a full u64 counter
using usec resolution, so that we can later have fine
grained TCP TS clock (RFC 7323), regardless of HZ value.

We try to refresh tp->tcp_mstamp only when necessary.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-05-16 14:00:00 -07:00 committed by David S. Miller
parent 9d4f97f97b
commit 385e20706f
4 changed files with 14 additions and 12 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
net/ipv4/tcp_ipv4.c
View file

@ -483,6 +483,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
skb = tcp_write_queue_head(sk);
BUG_ON(!skb);
skb_mstamp_get(&tp->tcp_mstamp);
remaining = icsk->icsk_rto -
min(icsk->icsk_rto,
tcp_time_stamp - tcp_skb_timestamp(skb));

21
net/ipv4/tcp_output.c
View file

@ -997,8 +997,8 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
BUG_ON(!skb || !tcp_skb_pcount(skb));
tp = tcp_sk(sk);
skb->skb_mstamp = tp->tcp_mstamp;
if (clone_it) {
skb_mstamp_get(&skb->skb_mstamp);
TCP_SKB_CB(skb)->tx.in_flight = TCP_SKB_CB(skb)->end_seq
- tp->snd_una;
tcp_rate_skb_sent(sk, skb);
@ -1906,7 +1906,6 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
const struct inet_connection_sock *icsk = inet_csk(sk);
u32 age, send_win, cong_win, limit, in_flight;
struct tcp_sock *tp = tcp_sk(sk);
struct skb_mstamp now;
struct sk_buff *head;
int win_divisor;
@ -1962,8 +1961,8 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,
}
head = tcp_write_queue_head(sk);
skb_mstamp_get(&now);
age = skb_mstamp_us_delta(&now, &head->skb_mstamp);
age = skb_mstamp_us_delta(&tp->tcp_mstamp, &head->skb_mstamp);
/* If next ACK is likely to come too late (half srtt), do not defer */
if (age < (tp->srtt_us >> 4))
goto send_now;
@ -2280,6 +2279,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
}
max_segs = tcp_tso_segs(sk, mss_now);
skb_mstamp_get(&tp->tcp_mstamp);
while ((skb = tcp_send_head(sk))) {
unsigned int limit;
@ -2291,7 +2291,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle,
if (unlikely(tp->repair) && tp->repair_queue == TCP_SEND_QUEUE) {
/* "skb_mstamp" is used as a start point for the retransmit timer */
skb_mstamp_get(&skb->skb_mstamp);
skb->skb_mstamp = tp->tcp_mstamp;
goto repair; /* Skip network transmission */
}
@ -2879,7 +2879,7 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
skb_headroom(skb) >= 0xFFFF)) {
struct sk_buff *nskb;
skb_mstamp_get(&skb->skb_mstamp);
skb->skb_mstamp = tp->tcp_mstamp;
nskb = __pskb_copy(skb, MAX_TCP_HEADER, GFP_ATOMIC);
err = nskb ? tcp_transmit_skb(sk, nskb, 0, GFP_ATOMIC) :
-ENOBUFS;
@ -3095,7 +3095,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority)
skb_reserve(skb, MAX_TCP_HEADER);
tcp_init_nondata_skb(skb, tcp_acceptable_seq(sk),
TCPHDR_ACK | TCPHDR_RST);
skb_mstamp_get(&skb->skb_mstamp);
skb_mstamp_get(&tcp_sk(sk)->tcp_mstamp);
/* Send it off. */
if (tcp_transmit_skb(sk, skb, 0, priority))
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTFAILED);
@ -3453,7 +3453,8 @@ int tcp_connect(struct sock *sk)
return -ENOBUFS;
tcp_init_nondata_skb(buff, tp->write_seq++, TCPHDR_SYN);
tp->retrans_stamp = tcp_time_stamp;
skb_mstamp_get(&tp->tcp_mstamp);
tp->retrans_stamp = tp->tcp_mstamp.stamp_jiffies;
tcp_connect_queue_skb(sk, buff);
tcp_ecn_send_syn(sk, buff);
@ -3572,7 +3573,6 @@ void tcp_send_ack(struct sock *sk)
skb_set_tcp_pure_ack(buff);
/* Send it off, this clears delayed acks for us. */
skb_mstamp_get(&buff->skb_mstamp);
tcp_transmit_skb(sk, buff, 0, (__force gfp_t)0);
}
EXPORT_SYMBOL_GPL(tcp_send_ack);
@ -3606,15 +3606,16 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent, int mib)
* send it.
*/
tcp_init_nondata_skb(skb, tp->snd_una - !urgent, TCPHDR_ACK);
skb_mstamp_get(&skb->skb_mstamp);
NET_INC_STATS(sock_net(sk), mib);
return tcp_transmit_skb(sk, skb, 0, (__force gfp_t)0);
}
/* Called from setsockopt( ... TCP_REPAIR ) */
void tcp_send_window_probe(struct sock *sk)
{
if (sk->sk_state == TCP_ESTABLISHED) {
tcp_sk(sk)->snd_wl1 = tcp_sk(sk)->rcv_nxt - 1;
skb_mstamp_get(&tcp_sk(sk)->tcp_mstamp);
tcp_xmit_probe_skb(sk, 0, LINUX_MIB_TCPWINPROBE);
}
}

1
net/ipv4/tcp_recovery.c
View file

@ -166,7 +166,6 @@ void tcp_rack_reo_timeout(struct sock *sk)
u32 timeout, prior_inflight;
prior_inflight = tcp_packets_in_flight(tp);
skb_mstamp_get(&tp->tcp_mstamp);
tcp_rack_detect_loss(sk, &timeout);
if (prior_inflight != tcp_packets_in_flight(tp)) {
if (inet_csk(sk)->icsk_ca_state != TCP_CA_Recovery) {

3
net/ipv4/tcp_timer.c
View file

@ -339,7 +339,7 @@ static void tcp_probe_timer(struct sock *sk)
*/
start_ts = tcp_skb_timestamp(tcp_send_head(sk));
if (!start_ts)
skb_mstamp_get(&tcp_send_head(sk)->skb_mstamp);
tcp_send_head(sk)->skb_mstamp = tp->tcp_mstamp;
else if (icsk->icsk_user_timeout &&
(s32)(tcp_time_stamp - start_ts) > icsk->icsk_user_timeout)
goto abort;
@ -561,6 +561,7 @@ void tcp_write_timer_handler(struct sock *sk)
goto out;
}
skb_mstamp_get(&tcp_sk(sk)->tcp_mstamp);
event = icsk->icsk_pending;
switch (event) {