From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx141.netapp.com (mx141.netapp.com [216.240.21.12]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "mx141.netapp.com", Issuer "VeriSign Class 3 International Server CA - G3" (not verified)) by huchra.bufferbloat.net (Postfix) with ESMTPS id E17DA21F1C4; Fri, 15 May 2015 01:22:18 -0700 (PDT) X-IronPort-AV: E=Sophos;i="5.13,433,1427785200"; d="scan'208,217";a="43632626" Received: from hioexcmbx03-prd.hq.netapp.com ([10.122.105.36]) by mx141-out.netapp.com with ESMTP; 15 May 2015 01:18:25 -0700 Received: from HIOEXCMBX07-PRD.hq.netapp.com (10.122.105.40) by hioexcmbx03-prd.hq.netapp.com (10.122.105.36) with Microsoft SMTP Server (TLS) id 15.0.1076.9; Fri, 15 May 2015 01:18:24 -0700 Received: from HIOEXCMBX07-PRD.hq.netapp.com ([::1]) by hioexcmbx07-prd.hq.netapp.com ([fe80::f07f:691d:89d:53b7%21]) with mapi id 15.00.0995.031; Fri, 15 May 2015 01:18:24 -0700 From: "Eggert, Lars" To: Aaron Wood Thread-Topic: [Bloat] [Cerowrt-devel] heisenbug: dslreports 16 flow test vs cablemodems Thread-Index: AQHQjsoYZWwSEwk1QUm/SgHdSFhrLZ19Jy4A Date: Fri, 15 May 2015 08:18:23 +0000 Message-ID: <8C015B1B-EFBA-4647-AD83-BAFDD16A4AF2@netapp.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.2100) x-originating-ip: [10.122.56.79] Content-Type: multipart/alternative; boundary="_000_8C015B1BEFBA4647AD83BAFDD16A4AF2netappcom_" MIME-Version: 1.0 Cc: "cake@lists.bufferbloat.net" , Greg White , "Klatsky, Carl" , "cerowrt-devel@lists.bufferbloat.net" , bloat Subject: Re: [Cerowrt-devel] [Bloat] heisenbug: dslreports 16 flow test vs cablemodems X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 May 2015 08:23:49 -0000 --_000_8C015B1BEFBA4647AD83BAFDD16A4AF2netappcom_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable On 2015-5-15, at 06:44, Aaron Wood > wrote: ICMP prioritization over TCP? Probably. Ping in parallel to TCP is a hacky way to measure latencies; not only becau= se of prioritization, but also because you don't measure TCP send/receive b= uffer latencies (and they can be large, auto-tuning is not so great.) You really need to embed timestamps in the TCP bytestream and echo them bac= k. See the recent netperf patch I sent. Lars --_000_8C015B1BEFBA4647AD83BAFDD16A4AF2netappcom_ Content-Type: text/html; charset="us-ascii" Content-ID: Content-Transfer-Encoding: quoted-printable On 2015-5-15, at 06:44, Aaron Wood <woody77@gmail.com> wrote:
ICMP prioritization over TCP?

Probably.

Ping in parallel to TCP is a hacky way to measure latencies= ; not only because of prioritization, but also because you don't measure TC= P send/receive buffer latencies (and they can be large, auto-tuning is not = so great.)

You really need to embed timestamps in the TCP bytestream a= nd echo them back. See the recent netperf patch I sent.

Lars
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