From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) by huchra.bufferbloat.net (Postfix) with ESMTP id B2BCD200666 for ; Sat, 9 Feb 2013 10:48:36 -0800 (PST) Received: from mailout-eu.gmx.com ([10.1.101.214]) by mrigmx.server.lan (mrigmx001) with ESMTP (Nemesis) id 0MfCFw-1UJ8fY44tO-00OlZU for ; Sat, 09 Feb 2013 19:48:34 +0100 Received: (qmail invoked by alias); 09 Feb 2013 18:48:34 -0000 Received: from 75-142-61-179.static.mtpk.ca.charter.com (EHLO hms-beagle.home.lan) [75.142.61.179] by mail.gmx.com (mp-eu014) with SMTP; 09 Feb 2013 19:48:34 +0100 X-Authenticated: #24211782 X-Provags-ID: V01U2FsdGVkX18SKIARSYMSyEhHanH+zRbwFwrc0koauS9aAewK8M SkhfBZbuXY8Zrm Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: text/plain; charset=iso-8859-1 From: this_is_not_my_name nor_is_this In-Reply-To: Date: Sat, 9 Feb 2013 10:48:26 -0800 Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Forums1000 X-Mailer: Apple Mail (2.1283) X-Y-GMX-Trusted: 0 Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] I am unable to pinpoint the source of bufferbloat X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 09 Feb 2013 18:48:37 -0000 Hi Jeroen, even though the experts already chimed in, let me try to elucidate what = I learned about netalyzr's latency probe. On Feb 9, 2013, at 01:52 , Forums1000 wrote: > Hi everyone, >=20 > Can anyone give some tips on how to diagnose the sources of = bufferbloat? According to the Netalyzr test at = http://netalyzr.icsi.berkeley.edu/, I have 550ms of upload bufferbloat. = I tried all kinds of stuff on my Windows 7 laptop: >=20 > - For the Intel(R) 82567LF Gigabit Network Connection, I put receive = and transmit buffers to the lowest value of 80 (80 bytes? 80 packets? I = don't know). I also disabled interrupt moderation.=20 > Result? Still 550ms. > - Then I connected my laptop directly to my cable modem, bypassing my = Mikrotik 450G router. Result? Still 550ms of bufferbloat.=20 > - Then I put a 100 megabit switch between the cable modem an the = laptop (as both cable modem and Intel NIC are gigabit). Result? Still = 550ms of upload buffer bloat. Netalyzr will only measure the latency of the slowest component = of the path between the test machine and the netalyzr servers, typically = that will be either a cable modem or a del modem. And indeed that = component was always constant in your measurements as was the latency. = So this is quite conclusive that uplink device has 550ms worth of worst = case buffering. >=20 > I'm out of ideas now. It seems I can't do anything at all to lower = bufferbloat. Or the Netalyzr test is broken?:-) Unlike typical real traffic, netalyzr uses an inelastic = unrelenting UDP flood to measure the absolute worst case buffering. Real = traffic typically will try to adjust itself to the existing bandwidth. If you follow Dave's advise and put a decent rate limiter and = modern queue management in your router (which by all means you should), = netalyzr will then measure the routers worst case buffering (which will = typically will be even worse than your modem's. 550ms actually is = relative decent for home equipment). But for real world cases modern = queue management will make all the difference in the world. So unless = your typical usage includes UDP floods your actual latency is (almost) = guaranteed to be much better. It seems your router is capable of running = the current OpenWRT release candidate (ar71xx I would guess, see = https://openwrt.org). best regards Sebastian >=20 > many thanks for your advice, > Jeroen >=20 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat