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tcp: add tcp_in_slow_start helper 

Add a helper to test the slow start condition in various congestion
control modules and other places. This is to prepare a slight improvement
in policy as to exactly when to slow start.

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Yuchung Cheng 2015-07-09 13:16:29 -07:00 committed by David S. Miller
parent 1007f59dce
commit 071d5080e3
11 changed files with 19 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
include/net/tcp.h
View File

@ -989,6 +989,11 @@ static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
#define TCP_INFINITE_SSTHRESH 0x7fffffff
static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
{
return tp->snd_cwnd <= tp->snd_ssthresh;
}
static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
{
return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
@ -1065,7 +1070,7 @@ static inline bool tcp_is_cwnd_limited(const struct sock *sk)
const struct tcp_sock *tp = tcp_sk(sk);
/* If in slow start, ensure cwnd grows to twice what was ACKed. */
if (tp->snd_cwnd <= tp->snd_ssthresh)
if (tcp_in_slow_start(tp))
return tp->snd_cwnd < 2 * tp->max_packets_out;
return tp->is_cwnd_limited;

2
net/ipv4/tcp_bic.c
View File

@ -146,7 +146,7 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
if (!tcp_is_cwnd_limited(sk))
return;
if (tp->snd_cwnd <= tp->snd_ssthresh)
if (tcp_in_slow_start(tp))
tcp_slow_start(tp, acked);
else {
bictcp_update(ca, tp->snd_cwnd);

2
net/ipv4/tcp_cong.c
View File

@ -413,7 +413,7 @@ void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
return;
/* In "safe" area, increase. */
if (tp->snd_cwnd <= tp->snd_ssthresh) {
if (tcp_in_slow_start(tp)) {
acked = tcp_slow_start(tp, acked);
if (!acked)
return;

4
net/ipv4/tcp_cubic.c
View File

@ -320,7 +320,7 @@ static void bictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
if (!tcp_is_cwnd_limited(sk))
return;
if (tp->snd_cwnd <= tp->snd_ssthresh) {
if (tcp_in_slow_start(tp)) {
if (hystart && after(ack, ca->end_seq))
bictcp_hystart_reset(sk);
acked = tcp_slow_start(tp, acked);
@ -439,7 +439,7 @@ static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)
ca->delay_min = delay;
/* hystart triggers when cwnd is larger than some threshold */
if (hystart && tp->snd_cwnd <= tp->snd_ssthresh &&
if (hystart && tcp_in_slow_start(tp) &&
tp->snd_cwnd >= hystart_low_window)
hystart_update(sk, delay);
}

2
net/ipv4/tcp_highspeed.c
View File

@ -116,7 +116,7 @@ static void hstcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
if (!tcp_is_cwnd_limited(sk))
return;
if (tp->snd_cwnd <= tp->snd_ssthresh)
if (tcp_in_slow_start(tp))
tcp_slow_start(tp, acked);
else {
/* Update AIMD parameters.

2
net/ipv4/tcp_htcp.c
View File

@ -236,7 +236,7 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
if (!tcp_is_cwnd_limited(sk))
return;
if (tp->snd_cwnd <= tp->snd_ssthresh)
if (tcp_in_slow_start(tp))
tcp_slow_start(tp, acked);
else {
/* In dangerous area, increase slowly.

2
net/ipv4/tcp_illinois.c
View File

@ -268,7 +268,7 @@ static void tcp_illinois_cong_avoid(struct sock *sk, u32 ack, u32 acked)
return;
/* In slow start */
if (tp->snd_cwnd <= tp->snd_ssthresh)
if (tcp_in_slow_start(tp))
tcp_slow_start(tp, acked);
else {

2
net/ipv4/tcp_metrics.c
View File

@ -461,7 +461,7 @@ void tcp_update_metrics(struct sock *sk)
tcp_metric_set(tm, TCP_METRIC_CWND,
tp->snd_cwnd);
}
} else if (tp->snd_cwnd > tp->snd_ssthresh &&
} else if (!tcp_in_slow_start(tp) &&
icsk->icsk_ca_state == TCP_CA_Open) {
/* Cong. avoidance phase, cwnd is reliable. */
if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))

2
net/ipv4/tcp_scalable.c
View File

@ -22,7 +22,7 @@ static void tcp_scalable_cong_avoid(struct sock *sk, u32 ack, u32 acked)
if (!tcp_is_cwnd_limited(sk))
return;
if (tp->snd_cwnd <= tp->snd_ssthresh)
if (tcp_in_slow_start(tp))
tcp_slow_start(tp, acked);
else
tcp_cong_avoid_ai(tp, min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT),

6
net/ipv4/tcp_vegas.c
View File

@ -225,7 +225,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 acked)
*/
diff = tp->snd_cwnd * (rtt-vegas->baseRTT) / vegas->baseRTT;
if (diff > gamma && tp->snd_cwnd <= tp->snd_ssthresh) {
if (diff > gamma && tcp_in_slow_start(tp)) {
/* Going too fast. Time to slow down
* and switch to congestion avoidance.
*/
@ -240,7 +240,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 acked)
tp->snd_cwnd = min(tp->snd_cwnd, (u32)target_cwnd+1);
tp->snd_ssthresh = tcp_vegas_ssthresh(tp);
} else if (tp->snd_cwnd <= tp->snd_ssthresh) {
} else if (tcp_in_slow_start(tp)) {
/* Slow start. */
tcp_slow_start(tp, acked);
} else {
@ -281,7 +281,7 @@ static void tcp_vegas_cong_avoid(struct sock *sk, u32 ack, u32 acked)
vegas->minRTT = 0x7fffffff;
}
/* Use normal slow start */
else if (tp->snd_cwnd <= tp->snd_ssthresh)
else if (tcp_in_slow_start(tp))
tcp_slow_start(tp, acked);
}

2
net/ipv4/tcp_veno.c
View File

@ -150,7 +150,7 @@ static void tcp_veno_cong_avoid(struct sock *sk, u32 ack, u32 acked)
veno->diff = (tp->snd_cwnd << V_PARAM_SHIFT) - target_cwnd;
if (tp->snd_cwnd <= tp->snd_ssthresh) {
if (tcp_in_slow_start(tp)) {
/* Slow start. */
tcp_slow_start(tp, acked);
} else {