From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: tcp wifi upload performance and lots of ACKs Date: Mon, 04 Jun 2012 13:09:11 -0700 Message-ID: <4FCD15E7.4080700@candelatech.com> References: <4FCCFE76.3060304@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev To: Daniel Baluta Return-path: Received: from mail.candelatech.com ([208.74.158.172]:49730 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751172Ab2FDUJO (ORCPT ); Mon, 4 Jun 2012 16:09:14 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 06/04/2012 12:22 PM, Daniel Baluta wrote: > On Mon, Jun 4, 2012 at 9:29 PM, Ben Greear wrote: >> I'm going some TCP performance testing on wifi -> LAN interface connections. >> With >> UDP, we can get around 250Mbps of payload throughput. With TCP, max is >> about 80Mbps. >> >> I think the problem is that there are way too many ACK packets, and >> bi-directional >> traffic on wifi interfaces really slows things down. (About 7000 pkts per >> second in >> upload direction, 2000 pps download. And the vast majority of the download >> pkts >> are 66 byte ACK pkts from what I can tell.) >> >> Kernel is 3.3.7+ >> >> Anyone know of any tuning parameters that would let the receiving socket >> wait a >> bit longer and send more ACK data in fewer packets? > > An ACK is generated after every second full sized segment or a timeout > expires. > > Currently, there is no way to tune these parameters. Here is an experimental > patch [1]. If anyone, thinks that this patch has a chance to get accepted > I will be happily try to further improve it. It looks like it could be useful for my case, but I would also want per-socket options to set the min/max ack delay so that the settings are not just system-wide. I can at least test this, and perhaps even hack on the code if you are not interested in the per-socket settings... Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com