From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH 6/6] tcp_cubic: enable high resolution ack time if needed Date: Thu, 10 Mar 2011 08:51:28 -0800 Message-ID: <20110310165329.281291096@vyatta.com> References: <20110310165119.224046957@vyatta.com> Cc: netdev@vger.kernel.org To: davem@davemloft.net, sangtae.ha@gmail.com, rhee@ncsu.edu Return-path: Received: from suva.vyatta.com ([76.74.103.44]:45018 "EHLO suva.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753358Ab1CJQ4W (ORCPT ); Thu, 10 Mar 2011 11:56:22 -0500 Content-Disposition: inline; filename=tcp-cubic-rtt-cong.patch Sender: netdev-owner@vger.kernel.org List-ID: This is a refined version of an earlier patch by Lucas Nussbaum. Cubic needs RTT values in milliseconds. If HZ < 1000 then the values will be too coarse. Signed-off-by: Stephen Hemminger --- a/net/ipv4/tcp_cubic.c 2011-03-10 08:35:59.968882888 -0800 +++ b/net/ipv4/tcp_cubic.c 2011-03-10 08:36:10.241016524 -0800 @@ -459,6 +459,10 @@ static int __init cubictcp_register(void /* divide by bic_scale and by constant Srtt (100ms) */ do_div(cube_factor, bic_scale * 10); + /* hystart needs ms clock resolution */ + if (hystart && HZ < 1000) + cubictcp.flags |= TCP_CONG_RTT_STAMP; + return tcp_register_congestion_control(&cubictcp); }