diff options
| author | David S. Miller <davem@davemloft.net> | 2016-11-21 13:20:17 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-11-21 13:20:17 -0500 |
| commit | 9e36ced6335be42e637a827b64f510f143dbb5a7 (patch) | |
| tree | 870e5c09c37890d286872c9ae22382d6bf336b37 /net/ipv4/tcp_veno.c | |
| parent | 2fcb58ab30deb63e49f238bf95d587740fab59c4 (diff) | |
| parent | e97991832a4ea4a5f47d65f068a4c966a2eb5730 (diff) | |
Merge branch 'tcp-cong-undo_cwnd-mandatory'
Florian Westphal says:
====================
tcp: make undo_cwnd mandatory for congestion modules
highspeed, illinois, scalable, veno and yeah congestion control algorithms
don't provide a 'cwnd_undo' function. This makes the stack default to a
'reno undo' which doubles cwnd. However, the ssthresh implementation of
these algorithms do not halve the slowstart threshold. This causes similar
issue as the one fixed for dctcp in ce6dd23329b1e ("dctcp: avoid bogus
doubling of cwnd after loss").
In light of this it seems better to remove the fallback and make undo_cwnd
mandatory.
First patch fixes those spots where reno undo seems incorrect by providing
.cwnd_undo functions, second patch removes the fallback.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/tcp_veno.c')
| -rw-r--r-- | net/ipv4/tcp_veno.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/net/ipv4/tcp_veno.c b/net/ipv4/tcp_veno.c index 40171e163cff..76005d4b8dfc 100644 --- a/net/ipv4/tcp_veno.c +++ b/net/ipv4/tcp_veno.c @@ -30,6 +30,7 @@ struct veno { u32 basertt; /* the min of all Veno rtt measurements seen (in usec) */ u32 inc; /* decide whether to increase cwnd */ u32 diff; /* calculate the diff rate */ + u32 loss_cwnd; /* cwnd when loss occured */ }; /* There are several situations when we must "re-start" Veno: @@ -193,6 +194,7 @@ static u32 tcp_veno_ssthresh(struct sock *sk) const struct tcp_sock *tp = tcp_sk(sk); struct veno *veno = inet_csk_ca(sk); + veno->loss_cwnd = tp->snd_cwnd; if (veno->diff < beta) /* in "non-congestive state", cut cwnd by 1/5 */ return max(tp->snd_cwnd * 4 / 5, 2U); @@ -201,9 +203,17 @@ static u32 tcp_veno_ssthresh(struct sock *sk) return max(tp->snd_cwnd >> 1U, 2U); } +static u32 tcp_veno_cwnd_undo(struct sock *sk) +{ + const struct veno *veno = inet_csk_ca(sk); + + return max(tcp_sk(sk)->snd_cwnd, veno->loss_cwnd); +} + static struct tcp_congestion_ops tcp_veno __read_mostly = { .init = tcp_veno_init, .ssthresh = tcp_veno_ssthresh, + .undo_cwnd = tcp_veno_cwnd_undo, .cong_avoid = tcp_veno_cong_avoid, .pkts_acked = tcp_veno_pkts_acked, .set_state = tcp_veno_state, |