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| author | Sangtae Ha <sangtae.ha@gmail.com> | 2011-03-14 07:52:18 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-03-14 15:54:42 -0700 |
| commit | b5ccd07337489fa9c9d32e0b628a2168b7953adf (patch) | |
| tree | 4c0bd60c5500440e6a5bb7086d54dedfb8eed815 | |
| parent | 2b4636a5f8ca547000f6aba24ec1c58f31f4a91d (diff) | |
| download | linux-b5ccd07337489fa9c9d32e0b628a2168b7953adf.tar.gz linux-b5ccd07337489fa9c9d32e0b628a2168b7953adf.tar.bz2 linux-b5ccd07337489fa9c9d32e0b628a2168b7953adf.zip | |
tcp_cubic: fix low utilization of CUBIC with HyStart
HyStart sets the initial exit point of slow start.
Suppose that HyStart exits at 0.5BDP in a BDP network and no history exists.
If the BDP of a network is large, CUBIC's initial cwnd growth may be
too conservative to utilize the link.
CUBIC increases the cwnd 20% per RTT in this case.
Signed-off-by: Sangtae Ha <sangtae.ha@gmail.com>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/tcp_cubic.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c index 7172c129ff19..90d92dd4cf13 100644 --- a/net/ipv4/tcp_cubic.c +++ b/net/ipv4/tcp_cubic.c @@ -270,6 +270,13 @@ static inline void bictcp_update(struct bictcp *ca, u32 cwnd) ca->cnt = 100 * cwnd; /* very small increment*/ } + /* + * The initial growth of cubic function may be too conservative + * when the available bandwidth is still unknown. + */ + if (ca->loss_cwnd == 0 && ca->cnt > 20) + ca->cnt = 20; /* increase cwnd 5% per RTT */ + /* TCP Friendly */ if (tcp_friendliness) { u32 scale = beta_scale; |