Commit 1b1fc3fd authored by Wei Wang's avatar Wei Wang Committed by David S. Miller

tcp: make congestion control optionally skip slow start after idle

Congestion control modules that want full control over congestion
control behavior do not want the cwnd modifications controlled by
the sysctl_tcp_slow_start_after_idle code path.
So skip those code paths for CC modules that use the cong_control()
API.
As an example, those cwnd effects are not desired for the BBR congestion
control algorithm.

Fixes: c0402760 ("tcp: new CC hook to set sending rate with rate_sample in any CA state")
Signed-off-by: default avatarWei Wang <weiwan@google.com>
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 82486aa6
...@@ -1234,10 +1234,12 @@ void tcp_cwnd_restart(struct sock *sk, s32 delta); ...@@ -1234,10 +1234,12 @@ void tcp_cwnd_restart(struct sock *sk, s32 delta);
static inline void tcp_slow_start_after_idle_check(struct sock *sk) static inline void tcp_slow_start_after_idle_check(struct sock *sk)
{ {
const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
struct tcp_sock *tp = tcp_sk(sk); struct tcp_sock *tp = tcp_sk(sk);
s32 delta; s32 delta;
if (!sysctl_tcp_slow_start_after_idle || tp->packets_out) if (!sysctl_tcp_slow_start_after_idle || tp->packets_out ||
ca_ops->cong_control)
return; return;
delta = tcp_time_stamp - tp->lsndtime; delta = tcp_time_stamp - tp->lsndtime;
if (delta > inet_csk(sk)->icsk_rto) if (delta > inet_csk(sk)->icsk_rto)
......
...@@ -1514,6 +1514,7 @@ static void tcp_cwnd_application_limited(struct sock *sk) ...@@ -1514,6 +1514,7 @@ static void tcp_cwnd_application_limited(struct sock *sk)
static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited)
{ {
const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
struct tcp_sock *tp = tcp_sk(sk); struct tcp_sock *tp = tcp_sk(sk);
/* Track the maximum number of outstanding packets in each /* Track the maximum number of outstanding packets in each
...@@ -1536,7 +1537,8 @@ static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) ...@@ -1536,7 +1537,8 @@ static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited)
tp->snd_cwnd_used = tp->packets_out; tp->snd_cwnd_used = tp->packets_out;
if (sysctl_tcp_slow_start_after_idle && if (sysctl_tcp_slow_start_after_idle &&
(s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto) (s32)(tcp_time_stamp - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto &&
!ca_ops->cong_control)
tcp_cwnd_application_limited(sk); tcp_cwnd_application_limited(sk);
/* The following conditions together indicate the starvation /* The following conditions together indicate the starvation
......
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