From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from emea01-db3-obe.outbound.protection.outlook.com (mail-db3on0076.outbound.protection.outlook.com [157.55.234.76]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client CN "mail.protection.outlook.com", Issuer "MSIT Machine Auth CA 2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 6D0D821F3AB for ; Wed, 3 Jun 2015 03:04:11 -0700 (PDT) Received: from VI1PR07MB0942.eurprd07.prod.outlook.com (25.161.110.147) by VI1PR07MB1215.eurprd07.prod.outlook.com (25.163.169.17) with Microsoft SMTP Server (TLS) id 15.1.172.22; Wed, 3 Jun 2015 10:04:07 +0000 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=kevin@darbyshire-bryant.me.uk; Received: from [IPv6:2001:470:183f:da2b::9b1c:6a15] (2001:470:183f:da2b::9b1c:6a15) by VI1PR07MB0942.eurprd07.prod.outlook.com (25.161.110.147) with Microsoft SMTP Server (TLS) id 15.1.184.17; Wed, 3 Jun 2015 10:04:06 +0000 Message-ID: <556ED111.7070603@darbyshire-bryant.me.uk> Date: Wed, 3 Jun 2015 11:04:01 +0100 From: Kevin Darbyshire-Bryant User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: References: <5566BD00.2010205@openwrt.org> In-Reply-To: <5566BD00.2010205@openwrt.org> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms040803080204090701030603" X-Originating-IP: [2001:470:183f:da2b::9b1c:6a15] X-ClientProxiedBy: DB5PR08CA0025.eurprd08.prod.outlook.com (25.163.102.163) To VI1PR07MB0942.eurprd07.prod.outlook.com (25.161.110.147) X-Microsoft-Antispam: UriScan:; BCL:0; PCL:0; RULEID:; SRVR:VI1PR07MB0942; UriScan:; BCL:0; PCL:0; RULEID:; SRVR:VI1PR07MB1215; X-Microsoft-Antispam-PRVS: X-Exchange-Antispam-Report-Test: UriScan:; X-Exchange-Antispam-Report-CFA-Test: BCL:0; PCL:0; RULEID:(601004)(520003)(5005006)(3002001); SRVR:VI1PR07MB0942; BCL:0; PCL:0; RULEID:; SRVR:VI1PR07MB0942; X-Forefront-PRVS: 05961EBAFC X-Forefront-Antispam-Report: SFV:NSPM; SFS:(10009020)(979002)(6009001)(199003)(51704005)(24454002)(479174004)(53754006)(189002)(83506001)(512944002)(97736004)(87976001)(36756003)(105586002)(2351001)(84326002)(81156007)(5001830100001)(4001540100001)(5001860100001)(33656002)(86362001)(46102003)(74482002)(65956001)(2950100001)(59896002)(92566002)(5890100001)(65806001)(40100003)(189998001)(450100001)(122386002)(101416001)(68736005)(62966003)(77156002)(64126003)(106356001)(4001350100001)(5001920100001)(5001960100002)(568964001)(107886002)(80316001)(64706001)(65816999)(87266999)(50986999)(76176999)(110136002)(42186005)(54356999)(31853002)(3826002)(5001840100002)(969003)(989001)(999001)(1009001)(1019001); DIR:OUT; SFP:1101; SCL:1; SRVR:VI1PR07MB0942; H:[IPv6:2001:470:183f:da2b::9b1c:6a15]; FPR:; SPF:None; PTR:InfoNoRecords; A:1; MX:1; LANG:en; Received-SPF: None (protection.outlook.com: darbyshire-bryant.me.uk does not designate permitted sender hosts) X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Jun 2015 10:04:06.3298 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR07MB0942 X-OriginatorOrg: darbyshire-bryant.me.uk Subject: Re: [Cerowrt-devel] Is ingress QoS worth the pain? 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: Wed, 03 Jun 2015 10:04:40 -0000 --------------ms040803080204090701030603 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable On 28/05/15 08:00, Steven Barth wrote: > Hi everyone, > > again a bit of a basic question, but what are the advantages of doing > ingress shaping in SQM? > > To me it wastes a lot of CPU cycles (decreases forwarding performance) > and you can't really "unsend" any packets from the ISP. What I mean is > in 99% of cases your internal forwarding capacity is usually (much?) > bigger than what the ISP sends to at any rate. > > What do I miss here? Some effects on TCP rate-limiting? > > As Dave has already said so well, *if* the ISP did sensible=20 shaping/limiting then I totally agree with you it's a waste of cycles. =20 Unfortunately it's a big if and I've seen some truly horrible behaviour, = especially on slow links where I think fair q'ing and latency control=20 are actually more important. Your point about 'unsending' packets is well made though, and since the=20 packet has made it this far and actually got to us it seems a shame to=20 shoot it. ECN would appear to be the best of both worlds, mark the=20 packet/flow that in an ideal world wouldn't have got through and so=20 signalling the other end to back off. Fitting smaller *managed* pipes here & there is counterintuitive but it=20 does help at the cost of bandwidth, something I'm more than prepared to=20 put up with for the improved latency control. But ideally fq_codel=20 really, really needs to be implemented by the ISP. --------------ms040803080204090701030603 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIINnDCC BjQwggQcoAMCAQICAR4wDQYJKoZIhvcNAQEFBQAwfTELMAkGA1UEBhMCSUwxFjAUBgNVBAoT DVN0YXJ0Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNp Z25pbmcxKTAnBgNVBAMTIFN0YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4XDTA3 MTAyNDIxMDE1NVoXDTE3MTAyNDIxMDE1NVowgYwxCzAJBgNVBAYTAklMMRYwFAYDVQQKEw1T dGFydENvbSBMdGQuMSswKQYDVQQLEyJTZWN1cmUgRGlnaXRhbCBDZXJ0aWZpY2F0ZSBTaWdu aW5nMTgwNgYDVQQDEy9TdGFydENvbSBDbGFzcyAxIFByaW1hcnkgSW50ZXJtZWRpYXRlIENs aWVudCBDQTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMcJg8zOLdgasSmkLhOr lr6KMoOMpohBllVHrdRvEg/q6r8jR+EK75xCGhR8ToREoqe7zM9/UnC6TS2y9UKTpT1v7RSM 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