From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: [PATCH] CUBIC v2.3 with new improved slow start Date: Wed, 29 Oct 2008 16:53:25 -0700 Message-ID: <4908F775.9040504@hp.com> References: <006001c93a0d$477d4e30$4a580e98@ncsu2cc0c3fa00> <20081029153928.3d47e26f@extreme> <000b01c93a1c$090222c0$6c01a8c0@RHEELAPTOP> <20081029164045.7422b68d@extreme> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Injong Rhee , Injong Rhee , netdev@vger.kernel.org To: Stephen Hemminger Return-path: Received: from g1t0026.austin.hp.com ([15.216.28.33]:48305 "EHLO g1t0026.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755042AbYJ2Xx3 (ORCPT ); Wed, 29 Oct 2008 19:53:29 -0400 In-Reply-To: <20081029164045.7422b68d@extreme> Sender: netdev-owner@vger.kernel.org List-ID: Stephen Hemminger wrote: > On Wed, 29 Oct 2008 19:14:03 -0400 > "Injong Rhee" wrote: > > >>>This looks like a good optimization, it obviously needs more testing >>>because Linux always seems to find new broken hardware. The areas >>>that need to be tested should include: >>> * MacOs has a broken version of delayed ack that might cause >>> HyStart to radically underestimate. >> >>We tested with FreeBSD. I presume that it covers MacOS. We will look into >>that. > > > No Darwin added some stupid code that holds off acks for up to 2 seconds. Is this Apple's reimplementation of the ACK avoidance heuristics in OSX they used to have in previous versions of MacOS with the Mentat TCP/IP stack? FWIW, HP-UX and Solaris also have ACK avoidance heursistics - they have a Mentat history - although both should be pretty good and neither should hold-off ACKs for two seconds... rick jones