From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-x236.google.com (mail-la0-x236.google.com [IPv6:2a00:1450:4010:c03::236]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 24A5C21F4F2 for ; Sun, 19 Apr 2015 12:17:26 -0700 (PDT) Received: by laat2 with SMTP id t2so112633795laa.1 for ; Sun, 19 Apr 2015 12:17:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=content-type:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=ICN/jqg/8fv5uDgtMhPXgKEt1k5oGgkp72ENE2x/jmU=; b=0reRNf9MdTocpf9tXoRMd0+fPFdGcRdsai25pl74nx1vmPNiZPsLL8CHKj5GErVFxG 1/cqO+gzAwWExsySq0a/57t/ZgKuKx8A6MsCLcUkV98ZTZfRg+H+yVyYLUzrgVj4/wnS WMT2+mxJ36OW1f4V+sLG3I1b+t/qvQoMcAuNXuJL+YziCpNNndt7lW/Uww0F05jm9yBd PL69o2EQzQ0RmItcPhtjiKURhmgrojBjtpZu0z+RmuyJupl95tXzUupNAufPYct6LYqu lriv4NPJLjxFpvlHx3AoTUWXf7vW38bNqcTkKOQDEU9jDlIVUC6tf3C0y17ALAMTazhH fhIQ== X-Received: by 10.112.63.165 with SMTP id h5mr12516028lbs.16.1429471044698; Sun, 19 Apr 2015 12:17:24 -0700 (PDT) Received: from bass.home.chromatix.fi (188-67-141-134.bb.dnainternet.fi. [188.67.141.134]) by mx.google.com with ESMTPSA id p3sm3832420lag.13.2015.04.19.12.16.03 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 19 Apr 2015 12:17:23 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2098\)) From: Jonathan Morton In-Reply-To: <87zj64hsy9.fsf@toke.dk> Date: Sun, 19 Apr 2015 22:15:54 +0300 Content-Transfer-Encoding: quoted-printable Message-Id: References: <87wq18jmak.fsf@toke.dk> <87oamkjfhf.fsf@toke.dk> <87k2x8jcnw.fsf@toke.dk> <87fv7wj9lh.fsf@toke.dk> <87zj64hsy9.fsf@toke.dk> To: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Mailer: Apple Mail (2.2098) Cc: bloat Subject: Re: [Bloat] DSLReports Speed Test has latency measurement built-in 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: Sun, 19 Apr 2015 19:17:55 -0000 > On 19 Apr, 2015, at 21:30, Toke H=C3=B8iland-J=C3=B8rgensen = wrote: >=20 >>> Why not? They can be a quite useful measure of how competing traffic >>> performs when bulk flows congest the link. Which for many >>> applications is more important then the latency experienced by the >>> bulk flow itself. >>=20 >> One clear objection is that ICMP is often prioritised when UDP is = not. >> So measuring with UDP gives a better indication in those cases. >> Measuring with a separate TCP flow, such as HTTPing, is better still >> by some measures, but most truly latency-sensitive traffic does use >> UDP. >=20 > Sure, well I tend to do both. Can't recall ever actually seeing any > performance difference between the UDP and ICMP latency measurements, > though... On a LAN, I usually see that ICMP gets a small bonus from being returned = by the kernel rather than needing to wake up a userspace process. That = might matter less when the target host is multicore; I=E2=80=99ve often = been using an old Thinkpad as a target. In any case, it=E2=80=99s a = constant factor without much dependence on network load. The one ISP I know of on this side of the pond which does any = prioritisation - there are many I don=E2=80=99t know about - prioritises = small packets in general, though I don=E2=80=99t know where they set = their threshold, specifically to help VoIP and gaming traffic. I = don=E2=80=99t think they treat ICMP specially beyond that. But = they=E2=80=99re a clueful one; there are many others less clueful. Meanwhile, I=E2=80=99m presently (briefly) in a very rural part of = Finland, where old 2G equipment (which I assume was redundant from early = populated-area deployments) was relocated to improve coverage. Twenty = miles from any decent-sized town, fifteen miles from the nearest 3G = tower, and about 7.5 miles from any worthwhile shops (ie. that sell = food). That means the local coverage is GPRS - not even EDGE. And I = brought some of the more portable components of my lab with me. This = should be fun=E2=80=A6 - Jonathan Morton