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| author | Neal Cardwell <ncardwell@google.com> | 2017-07-14 17:49:23 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-07-15 14:43:29 -0700 |
| commit | 79135b89b8af304456bd67916b80116ddf03d7b6 (patch) | |
| tree | c339cd662873800db6d40eb88e4b14a2f42a7781 /net/ipv4/tcp_bbr.c | |
| parent | f19fd62dafaf1ed6cf615dba655b82fa9df59074 (diff) | |
| download | linux-79135b89b8af304456bd67916b80116ddf03d7b6.tar.gz linux-79135b89b8af304456bd67916b80116ddf03d7b6.tar.bz2 linux-79135b89b8af304456bd67916b80116ddf03d7b6.zip | |
tcp_bbr: introduce bbr_init_pacing_rate_from_rtt() helper
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>
Diffstat (limited to 'net/ipv4/tcp_bbr.c')
| -rw-r--r-- | net/ipv4/tcp_bbr.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c index 29e23b851b97..3276140c2506 100644 --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -221,6 +221,23 @@ 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 @@ -805,7 +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 */ @@ -821,11 +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; |