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authorKevin Yang <yyd@google.com>2018-08-22 17:43:14 -0400
committerDavid S. Miller <davem@davemloft.net>2018-08-22 21:45:32 -0700
commitfb99886224294b2291d267da41395022fa4200e2 (patch)
tree5830e096f7e98a9033c37ef4d1d1dac8221e685e /net/ipv4/tcp_bbr.c
parentipv4: tcp: send zero IPID for RST and ACK sent in SYN-RECV and TIME-WAIT state (diff)
downloadlinux-dev-fb99886224294b2291d267da41395022fa4200e2.tar.xz
linux-dev-fb99886224294b2291d267da41395022fa4200e2.zip
tcp_bbr: add bbr_check_probe_rtt_done() helper
This patch add a helper function bbr_check_probe_rtt_done() to 1. check the condition to see if bbr should exit probe_rtt mode; 2. process the logic of exiting probe_rtt mode. Fixes: 0f8782ea1497 ("tcp_bbr: add BBR congestion control") Signed-off-by: Kevin Yang <yyd@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Reviewed-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.c34
1 files changed, 18 insertions, 16 deletions
diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index 13d34427ca3d..fd7bccf36a26 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -95,11 +95,10 @@ struct bbr {
u32 mode:3, /* current bbr_mode in state machine */
prev_ca_state:3, /* CA state on previous ACK */
packet_conservation:1, /* use packet conservation? */
- restore_cwnd:1, /* decided to revert cwnd to old value */
round_start:1, /* start of packet-timed tx->ack round? */
idle_restart:1, /* restarting after idle? */
probe_rtt_round_done:1, /* a BBR_PROBE_RTT round at 4 pkts? */
- unused:12,
+ unused:13,
lt_is_sampling:1, /* taking long-term ("LT") samples now? */
lt_rtt_cnt:7, /* round trips in long-term interval */
lt_use_bw:1; /* use lt_bw as our bw estimate? */
@@ -396,17 +395,11 @@ static bool bbr_set_cwnd_to_recover_or_restore(
cwnd = tcp_packets_in_flight(tp) + acked;
} else if (prev_state >= TCP_CA_Recovery && state < TCP_CA_Recovery) {
/* Exiting loss recovery; restore cwnd saved before recovery. */
- bbr->restore_cwnd = 1;
+ cwnd = max(cwnd, bbr->prior_cwnd);
bbr->packet_conservation = 0;
}
bbr->prev_ca_state = state;
- if (bbr->restore_cwnd) {
- /* Restore cwnd after exiting loss recovery or PROBE_RTT. */
- cwnd = max(cwnd, bbr->prior_cwnd);
- bbr->restore_cwnd = 0;
- }
-
if (bbr->packet_conservation) {
*new_cwnd = max(cwnd, tcp_packets_in_flight(tp) + acked);
return true; /* yes, using packet conservation */
@@ -748,6 +741,20 @@ static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs)
bbr_reset_probe_bw_mode(sk); /* we estimate queue is drained */
}
+static void bbr_check_probe_rtt_done(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct bbr *bbr = inet_csk_ca(sk);
+
+ if (!(bbr->probe_rtt_done_stamp &&
+ after(tcp_jiffies32, bbr->probe_rtt_done_stamp)))
+ return;
+
+ bbr->min_rtt_stamp = tcp_jiffies32; /* wait a while until PROBE_RTT */
+ tp->snd_cwnd = max(tp->snd_cwnd, bbr->prior_cwnd);
+ bbr_reset_mode(sk);
+}
+
/* The goal of PROBE_RTT mode is to have BBR flows cooperatively and
* periodically drain the bottleneck queue, to converge to measure the true
* min_rtt (unloaded propagation delay). This allows the flows to keep queues
@@ -806,12 +813,8 @@ static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs)
} else if (bbr->probe_rtt_done_stamp) {
if (bbr->round_start)
bbr->probe_rtt_round_done = 1;
- if (bbr->probe_rtt_round_done &&
- after(tcp_jiffies32, bbr->probe_rtt_done_stamp)) {
- bbr->min_rtt_stamp = tcp_jiffies32;
- bbr->restore_cwnd = 1; /* snap to prior_cwnd */
- bbr_reset_mode(sk);
- }
+ if (bbr->probe_rtt_round_done)
+ bbr_check_probe_rtt_done(sk);
}
}
/* Restart after idle ends only once we process a new S/ACK for data */
@@ -862,7 +865,6 @@ static void bbr_init(struct sock *sk)
bbr->has_seen_rtt = 0;
bbr_init_pacing_rate_from_rtt(sk);
- bbr->restore_cwnd = 0;
bbr->round_start = 0;
bbr->idle_restart = 0;
bbr->full_bw_reached = 0;