[TCP]: simplify microsecond rtt sampling
Simplify the code that comuputes microsecond rtt estimate used
by TCP Vegas. Move the callback out of the RTT sampler and into
the end of the ack cleanup.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 3e98b57..e430656 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -548,10 +548,9 @@
* To save cycles in the RFC 1323 implementation it was better to break
* it up into three procedures. -- erics
*/
-static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt, u32 *usrtt)
+static void tcp_rtt_estimator(struct sock *sk, const __u32 mrtt)
{
struct tcp_sock *tp = tcp_sk(sk);
- const struct inet_connection_sock *icsk = inet_csk(sk);
long m = mrtt; /* RTT */
/* The following amusing code comes from Jacobson's
@@ -610,9 +609,6 @@
tp->mdev_max = tp->rttvar = max(tp->mdev, TCP_RTO_MIN);
tp->rtt_seq = tp->snd_nxt;
}
-
- if (icsk->icsk_ca_ops->rtt_sample)
- icsk->icsk_ca_ops->rtt_sample(sk, *usrtt);
}
/* Calculate rto without backoff. This is the second half of Van Jacobson's
@@ -1921,7 +1917,7 @@
/* Read draft-ietf-tcplw-high-performance before mucking
* with this code. (Superceeds RFC1323)
*/
-static void tcp_ack_saw_tstamp(struct sock *sk, u32 *usrtt, int flag)
+static void tcp_ack_saw_tstamp(struct sock *sk, int flag)
{
/* RTTM Rule: A TSecr value received in a segment is used to
* update the averaged RTT measurement only if the segment
@@ -1940,13 +1936,13 @@
*/
struct tcp_sock *tp = tcp_sk(sk);
const __u32 seq_rtt = tcp_time_stamp - tp->rx_opt.rcv_tsecr;
- tcp_rtt_estimator(sk, seq_rtt, usrtt);
+ tcp_rtt_estimator(sk, seq_rtt);
tcp_set_rto(sk);
inet_csk(sk)->icsk_backoff = 0;
tcp_bound_rto(sk);
}
-static void tcp_ack_no_tstamp(struct sock *sk, u32 seq_rtt, u32 *usrtt, int flag)
+static void tcp_ack_no_tstamp(struct sock *sk, u32 seq_rtt, int flag)
{
/* We don't have a timestamp. Can only use
* packets that are not retransmitted to determine
@@ -1960,21 +1956,21 @@
if (flag & FLAG_RETRANS_DATA_ACKED)
return;
- tcp_rtt_estimator(sk, seq_rtt, usrtt);
+ tcp_rtt_estimator(sk, seq_rtt);
tcp_set_rto(sk);
inet_csk(sk)->icsk_backoff = 0;
tcp_bound_rto(sk);
}
static inline void tcp_ack_update_rtt(struct sock *sk, const int flag,
- const s32 seq_rtt, u32 *usrtt)
+ const s32 seq_rtt)
{
const struct tcp_sock *tp = tcp_sk(sk);
/* Note that peer MAY send zero echo. In this case it is ignored. (rfc1323) */
if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr)
- tcp_ack_saw_tstamp(sk, usrtt, flag);
+ tcp_ack_saw_tstamp(sk, flag);
else if (seq_rtt >= 0)
- tcp_ack_no_tstamp(sk, seq_rtt, usrtt, flag);
+ tcp_ack_no_tstamp(sk, seq_rtt, flag);
}
static inline void tcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
@@ -2054,20 +2050,27 @@
return acked;
}
+static inline u32 tcp_usrtt(const struct sk_buff *skb)
+{
+ struct timeval tv, now;
+
+ do_gettimeofday(&now);
+ skb_get_timestamp(skb, &tv);
+ return (now.tv_sec - tv.tv_sec) * 1000000 + (now.tv_usec - tv.tv_usec);
+}
/* Remove acknowledged frames from the retransmission queue. */
-static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p, s32 *seq_usrtt)
+static int tcp_clean_rtx_queue(struct sock *sk, __s32 *seq_rtt_p)
{
struct tcp_sock *tp = tcp_sk(sk);
+ const struct inet_connection_sock *icsk = inet_csk(sk);
struct sk_buff *skb;
__u32 now = tcp_time_stamp;
int acked = 0;
__s32 seq_rtt = -1;
- struct timeval usnow;
u32 pkts_acked = 0;
-
- if (seq_usrtt)
- do_gettimeofday(&usnow);
+ void (*rtt_sample)(struct sock *sk, u32 usrtt)
+ = icsk->icsk_ca_ops->rtt_sample;
while ((skb = skb_peek(&sk->sk_write_queue)) &&
skb != sk->sk_send_head) {
@@ -2107,16 +2110,11 @@
tp->retrans_out -= tcp_skb_pcount(skb);
acked |= FLAG_RETRANS_DATA_ACKED;
seq_rtt = -1;
- } else if (seq_rtt < 0)
+ } else if (seq_rtt < 0) {
seq_rtt = now - scb->when;
- if (seq_usrtt) {
- struct timeval tv;
-
- skb_get_timestamp(skb, &tv);
- *seq_usrtt = (usnow.tv_sec - tv.tv_sec) * 1000000
- + (usnow.tv_usec - tv.tv_usec);
+ if (rtt_sample)
+ (*rtt_sample)(sk, tcp_usrtt(skb));
}
-
if (sacked & TCPCB_SACKED_ACKED)
tp->sacked_out -= tcp_skb_pcount(skb);
if (sacked & TCPCB_LOST)
@@ -2126,8 +2124,11 @@
!before(scb->end_seq, tp->snd_up))
tp->urg_mode = 0;
}
- } else if (seq_rtt < 0)
+ } else if (seq_rtt < 0) {
seq_rtt = now - scb->when;
+ if (rtt_sample)
+ (*rtt_sample)(sk, tcp_usrtt(skb));
+ }
tcp_dec_pcount_approx(&tp->fackets_out, skb);
tcp_packets_out_dec(tp, skb);
__skb_unlink(skb, &sk->sk_write_queue);
@@ -2135,8 +2136,7 @@
}
if (acked&FLAG_ACKED) {
- const struct inet_connection_sock *icsk = inet_csk(sk);
- tcp_ack_update_rtt(sk, acked, seq_rtt, seq_usrtt);
+ tcp_ack_update_rtt(sk, acked, seq_rtt);
tcp_ack_packets_out(sk, tp);
if (icsk->icsk_ca_ops->pkts_acked)
@@ -2299,7 +2299,6 @@
u32 ack = TCP_SKB_CB(skb)->ack_seq;
u32 prior_in_flight;
s32 seq_rtt;
- s32 seq_usrtt = 0;
int prior_packets;
/* If the ack is newer than sent or older than previous acks
@@ -2352,8 +2351,7 @@
prior_in_flight = tcp_packets_in_flight(tp);
/* See if we can take anything off of the retransmit queue. */
- flag |= tcp_clean_rtx_queue(sk, &seq_rtt,
- icsk->icsk_ca_ops->rtt_sample ? &seq_usrtt : NULL);
+ flag |= tcp_clean_rtx_queue(sk, &seq_rtt);
if (tp->frto_counter)
tcp_process_frto(sk, prior_snd_una);
@@ -4242,7 +4240,7 @@
*/
if (tp->rx_opt.saw_tstamp && tp->rx_opt.rcv_tsecr &&
!tp->srtt)
- tcp_ack_saw_tstamp(sk, NULL, 0);
+ tcp_ack_saw_tstamp(sk, 0);
if (tp->rx_opt.tstamp_ok)
tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;