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authorNeal Cardwell <ncardwell@google.com>2017-07-14 17:49:23 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-08-11 08:33:55 -0700
commit6d7b91fccff92e55d2dae3b115af6fb5bc177504 (patch)
treecf2338cb552b408aadbd7669c2e871a7cb64787a /net
parentb670ddb7174ce9e47fccd110d097bf841170f61d (diff)
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tcp_bbr: introduce bbr_init_pacing_rate_from_rtt() helper
[ Upstream commit 79135b89b8af304456bd67916b80116ddf03d7b6 ] Introduce a helper to initialize the BBR pacing rate unconditionally, based on the current cwnd and RTT estimate. This is a pure refactor, but is needed for two following fixes. Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control") Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_bbr.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index 14e0eba7aa7a..e69c8b44568a 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -222,6 +222,23 @@ static u32 bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain)
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
@@ -806,7 +823,6 @@ 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 */
@@ -822,11 +838,8 @@ 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;