tcp_bbr: introduce bbr_init_pacing_rate_from_rtt() helper

[karo-tx-linux.git] / net / ipv4 / tcp_bbr.c

diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index dbcc9352a48f07a12484e45f3baf0a733e244f75..3276140c25067c7fe56ed742aa807087b5bfa35d 100644 (file)
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -211,6 +211,33 @@ static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain)
        return rate >> BW_SCALE;
 }
 
+/* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */
+static u32 bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain)
+{
+       u64 rate = bw;
+
+       rate = bbr_rate_bytes_per_sec(sk, rate, gain);
+       rate = min_t(u64, rate, sk->sk_max_pacing_rate);
+       return rate;
+}
+
+/* Initialize pacing rate to: high_gain * init_cwnd / RTT. */
+static void bbr_init_pacing_rate_from_rtt(struct sock *sk)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+       u64 bw;
+       u32 rtt_us;
+
+       if (tp->srtt_us) {              /* any RTT sample yet? */
+               rtt_us = max(tp->srtt_us >> 3, 1U);
+       } else {                         /* no RTT sample yet */
+               rtt_us = USEC_PER_MSEC;  /* use nominal default RTT */
+       }
+       bw = (u64)tp->snd_cwnd * BW_UNIT;
+       do_div(bw, rtt_us);
+       sk->sk_pacing_rate = bbr_bw_to_pacing_rate(sk, bw, bbr_high_gain);
+}
+
 /* Pace using current bw estimate and a gain factor. In order to help drive the
  * network toward lower queues while maintaining high utilization and low
  * latency, the average pacing rate aims to be slightly (~1%) lower than the
@@ -220,12 +247,9 @@ static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain)
  */
 static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain)
 {
-       struct bbr *bbr = inet_csk_ca(sk);
-       u64 rate = bw;
+       u32 rate = bbr_bw_to_pacing_rate(sk, bw, gain);
 
-       rate = bbr_rate_bytes_per_sec(sk, rate, gain);
-       rate = min_t(u64, rate, sk->sk_max_pacing_rate);
-       if (bbr->mode != BBR_STARTUP || rate > sk->sk_pacing_rate)
+       if (bbr_full_bw_reached(sk) || rate > sk->sk_pacing_rate)
                sk->sk_pacing_rate = rate;
 }
 
@@ -798,7 +822,6 @@ static void bbr_init(struct sock *sk)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        struct bbr *bbr = inet_csk_ca(sk);
-       u64 bw;
 
        bbr->prior_cwnd = 0;
        bbr->tso_segs_goal = 0;  /* default segs per skb until first ACK */
@@ -814,11 +837,8 @@ static void bbr_init(struct sock *sk)
 
        minmax_reset(&bbr->bw, bbr->rtt_cnt, 0);  /* init max bw to 0 */
 
-       /* Initialize pacing rate to: high_gain * init_cwnd / RTT. */
-       bw = (u64)tp->snd_cwnd * BW_UNIT;
-       do_div(bw, (tp->srtt_us >> 3) ? : USEC_PER_MSEC);
        sk->sk_pacing_rate = 0;         /* force an update of sk_pacing_rate */
-       bbr_set_pacing_rate(sk, bw, bbr_high_gain);
+       bbr_init_pacing_rate_from_rtt(sk);
 
        bbr->restore_cwnd = 0;
        bbr->round_start = 0;