From owner-freebsd-net@FreeBSD.ORG Wed Nov 30 13:59:51 2011 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 26E1E106566C for ; Wed, 30 Nov 2011 13:59:51 +0000 (UTC) (envelope-from hapvbk@yahoo.co.uk) Received: from nm25-vm6.bullet.mail.ukl.yahoo.com (nm25-vm6.bullet.mail.ukl.yahoo.com [217.146.177.150]) by mx1.freebsd.org (Postfix) with SMTP id 99B918FC0C for ; Wed, 30 Nov 2011 13:59:50 +0000 (UTC) Received: from [217.146.183.182] by nm25.bullet.mail.ukl.yahoo.com with NNFMP; 30 Nov 2011 13:59:49 -0000 Received: from [77.238.184.71] by tm13.bullet.mail.ukl.yahoo.com with NNFMP; 30 Nov 2011 13:59:48 -0000 Received: from [127.0.0.1] by smtp140.mail.ukl.yahoo.com with NNFMP; 30 Nov 2011 13:59:48 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1322661588; bh=POqPOKr+rWiXh2dVQRawKjGuf3aanfsJFb3pdi9RaOg=; h=X-Yahoo-Newman-Id:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Message-ID:From:To:Cc:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:Importance:X-Mailer:X-MimeOLE; b=QyV8O/MqmdJe+8XuSeolBD2WtHqCpfPAYpgrF04xH24wROK80Iv8grHbO3cGrdXnOpKXZ+UmPGFLgotUVzQMYVwYR001itzwIVoUTKv7NqS0a3feebLeKHha0UFN86P1yrkgZUHakGl0jDXpGmdEHuojZn/NBJ2HQrTdUW7Qm/E= X-Yahoo-Newman-Id: 923405.23602.bm@smtp140.mail.ukl.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: QpQGKzEVM1m0rJrtMXibu3f6MeXsd5YQJvPsC6TyqHU_dI6 u9h9ZzxdwEPMt1ltO.07bOfagJK74gxNp3_KXxCWabx3mbwbcZfXKbPR4Ogy .GrYnKXTVLXVWwmsM1x0vsvqVdSte8APAsdjQsxxu2MM8irCGMC4p3_v7EIL P2E96.UXuoX5Fua9eH7H4obxPMMMffLGpAqoW4blvw_3NqKT0hJ5o3QvTOEb s2Gsgl3X54Oge5ztv5JQkpkW59iariWQ6rRgoVg8w0o2HpwFgbz_BTquyFhx NEZXHhJYnI3gdXL5QKx0Eu24o5DYjjmxVlvA7Oo68hybct1hg.8.1OwgRykM CdAL0jqPKE8x6dWLjscp1uUpEBr_15RfP.j4u8RU- X-Yahoo-SMTP: xBpCc9iswBApASleyiIs9lcZMA-- Received: from PC (hapvbk@66.11.191.2 with login) by smtp140.mail.ukl.yahoo.com with SMTP; 30 Nov 2011 13:59:48 +0000 GMT Message-ID: <5939430EC6AF43B79CB9BE99940E9B91@PC> From: "Viet-Ha Pham" To: "Bernhard Schmidt" References: <69C75F6ECC9646C79374299EDF0E4304@PC> In-Reply-To: Date: Wed, 30 Nov 2011 08:59:45 -0500 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3538.513 X-MimeOLE: Produced By Microsoft MimeOLE V15.4.3538.513 Cc: freebsd-net@freebsd.org, Adrian Chadd Subject: Re: Wifi throughput test issue (FreeBSD 8.2) X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 30 Nov 2011 13:59:51 -0000 Hi Bernhard, Thanks so much for your quick reply. I did not test this scenario with 9.0 or later so I don't have any idea if it's working ok or not. I'll do it next. For the debug options, I'll can do it right away and get back with more infor. HAPV -----Original Message----- From: Bernhard Schmidt Sent: Wednesday, November 30, 2011 8:34 AM To: Viet-Ha Pham Cc: freebsd-net@freebsd.org ; Adrian Chadd Subject: Re: Wifi throughput test issue (FreeBSD 8.2) On Wed, Nov 30, 2011 at 13:37, Viet-Ha Pham wrote: > Hello, > > > I am doing some throughput measurement for Wifi network. I am using > jperf/iperf to generate traffic (at the transmitter) and measure the > throughput (at the receiver). The transmitter and receiver are running > FreeBSD 8.2, using CM9-GP as the Wifi NIC. We are testing AWGN channel. > So, the transmitter and receiver are connected by cables, txpower on both > sides is set lower than the max (ranging from 0 to 10), AWGN noise is > injected in the middle of the cable. > > We measure the maximum throughput at each transmission rate. Transmitter > is a STA, receiver is an AP. We fix the unicast rate at the transmitter to > 54 Mbps (using "ifconfig ... ucastrate" command). The packet size is set > to 400 Bytes, UDP protocol is used and the transmit bandwidth is set to 30 > Mbps in order to flood the transmission channel (to push it to its limit). > At first, at the receiver (AP) the measured throughput is about 12 Mbps. > Then I fix the unicast rate at the receiver (using ifconfig again) to 54 > Mbps. The measured throughput increases to 20 Mbps. I set the unicast rate > at the receiver to autoselect again, the throughput is still 20 Mbps. > > When I switch the rate at the receiver, there are multiple message > displayed on the screen of the transmitter: "wlan0: > ieee80211_new_state_locked: pending RUN -> AUTH transition lost". This > message is repeated for many times (at least 20). > > I repeated the test with all transmission rates, change the packet size > and still observe the same thing: a throughput improvement of about 30% is > observed when I switch the unicast rate at the receiver and the > improvement is still there when I switch the unicast rate back to > autoselect. The same thing is observed in modes a and g. The same thing is > observed if the unicast rate at the receiver is set different from the > unicast rate at the transmitter. > > > > I spent time to look at the kernel source codes but I did not find a solid > answer for this. Please help me to identify the problem and the answer. > > > My question is: > > 1. Why do I have that throughput improvement when I switch the rate like > that? > 2. Is it a bug in the driver? I think so, the driver might ignore/do some fancy stuff with a fixed ucastrate. @Adrian, do you know if ath_rate_sample has some debug options in that regard? > 3. What does the error/infor message on the transmitter mean? It might mean a lot of things, you should probably enable additional debug options to get a clue about what's going on. Btw, do you also see that behavior on HEAD (or at least the latest 9.x release/rc)? -- Bernhard