[net,3/3] tcp_bbr: reset long-term bandwidth sampling on loss recovery undo

Message ID 20171207174332.17689-4-ncardwell@google.com
State Accepted
Delegated to: David Miller
Headers show
Series
  • TCP BBR sampling fixes for loss recovery undo
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Commit Message

Neal Cardwell Dec. 7, 2017, 5:43 p.m.
Fix BBR so that upon notification of a loss recovery undo BBR resets
long-term bandwidth sampling.

Under high reordering, reordering events can be interpreted as loss.
If the reordering and spurious loss estimates are high enough, this
can cause BBR to spuriously estimate that we are seeing loss rates
high enough to trigger long-term bandwidth estimation. To avoid that
problem, this commit resets long-term bandwidth sampling on loss
recovery undo events.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
---
 net/ipv4/tcp_bbr.c | 1 +
 1 file changed, 1 insertion(+)

Patch

diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c
index ab3ff14ea7f7..8322f26e770e 100644
--- a/net/ipv4/tcp_bbr.c
+++ b/net/ipv4/tcp_bbr.c
@@ -878,6 +878,7 @@  static u32 bbr_undo_cwnd(struct sock *sk)
 
 	bbr->full_bw = 0;   /* spurious slow-down; reset full pipe detection */
 	bbr->full_bw_cnt = 0;
+	bbr_reset_lt_bw_sampling(sk);
 	return tcp_sk(sk)->snd_cwnd;
 }