From mboxrd@z Thu Jan 1 00:00:00 1970 From: dormando Subject: Re: 3 packet TCP window limit? Date: Wed, 5 May 2010 13:01:19 -0700 (PDT) Message-ID: References: <4BE171EC.20904@athenacr.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: netdev@vger.kernel.org To: Brian Bloniarz Return-path: Received: from rydia.net ([216.218.163.68]:52899 "EHLO mail.rydia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753214Ab0EEUBx (ORCPT ); Wed, 5 May 2010 16:01:53 -0400 In-Reply-To: <4BE171EC.20904@athenacr.com> Sender: netdev-owner@vger.kernel.org List-ID: > This sounds like TCP slow start. > > http://en.wikipedia.org/wiki/Slow-start > > As far as tunables you might want to play with the initcwnd route > flag (see "ip route help") Ah, yes, initcwnd was it. I'm well aware of TCP Congestion control / slow start / etc. However I couldn't find the damn tunable for it :) ssthresh/tso/etc didn't seem to unwedge it. Felt like describing it in the most generic way possible would help :) Other OS's appear to have a larger initcwnd. As do commercial load balancers. The default of 3 seems to be tuned for 56k dialup modems. I'm a little surprised that none of the pluggable TCP congestion control algorithms changed this value. I went through all of them except for tcp_yeah. Anyway, thanks and sorry for the nearly off-topic post here. I see some google papers on bumping initcwnd to 10... but I guess that's not linux's deal yet.