From: Sangtae Ha 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 Acked-by: Stephen Hemminger --- net/ipv4/tcp_cubic.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) --- a/net/ipv4/tcp_cubic.c 2011-03-14 08:32:46.347993869 -0700 +++ b/net/ipv4/tcp_cubic.c 2011-03-14 10:57:00.846549449 -0700 @@ -270,6 +270,13 @@ static inline void bictcp_update(struct 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; -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html