From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH] Make CUBIC Hystart more robust to RTT variations Date: Thu, 10 Mar 2011 15:28:48 -0800 Message-ID: <20110310152848.7b515511@nehalam> References: <20110308093215.GA23842@xanadu.blop.info> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Sangtae Ha To: Lucas Nussbaum Return-path: Received: from mail.vyatta.com ([76.74.103.46]:45609 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752707Ab1CJX2v (ORCPT ); Thu, 10 Mar 2011 18:28:51 -0500 In-Reply-To: <20110308093215.GA23842@xanadu.blop.info> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 8 Mar 2011 10:32:15 +0100 Lucas Nussbaum wrote: > CUBIC Hystart uses two heuristics to exit slow start earlier, before > losses start to occur. Unfortunately, it tends to exit slow start far too > early, causing poor performance since convergence to the optimal cwnd is > then very slow. This was reported in > http://permalink.gmane.org/gmane.linux.network/188169 and > https://partner-bugzilla.redhat.com/show_bug.cgi?id=616985 Ignore the RHEL bug. RHEL 5 ships with TCP BIC (not CUBIC) by default. There are many research papers which show that BIC is too aggressive, and not fair. --