From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 4D0193B29E for ; Sat, 19 Oct 2019 17:22:53 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1571520164; bh=/oXKGTIWjAUPbYoK90oc9JOmj9AnfNVvZbNp/7ioa4c=; h=X-UI-Sender-Class:Subject:From:In-Reply-To:Date:Cc:References:To; b=TNdIPFn2swz70DQLd2pEApQTyPf/WFkA1tJzR3pIyff1gKK5f0ZMTLZJTPlTEwtPw aI/WZRg8JMU4MiQS5wB6jK6YJNXMNNOBcz8KFnfWci0N9m90piI+0ZRSVrDa8+j+hV ab8hsvECy9wQuk+U1kZcHKxHGPRp8gx/PkgEwDi8= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from hms-beagle2.lan ([77.10.105.152]) by mail.gmx.com (mrgmx005 [212.227.17.190]) with ESMTPSA (Nemesis) id 1N8GQs-1hzxJc3BK4-0149j0; Sat, 19 Oct 2019 23:22:44 +0200 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.4 \(3445.104.11\)) From: Sebastian Moeller In-Reply-To: <87a79wd67g.fsf@toke.dk> Date: Sat, 19 Oct 2019 23:22:42 +0200 Cc: Johannes Berg , Kan Yan , Make-Wifi-fast Content-Transfer-Encoding: quoted-printable Message-Id: References: <157115993755.2500430.12214017471129215800.stgit@toke.dk> <157115994190.2500430.14955682016008497593.stgit@toke.dk> <87o8yfg0zo.fsf@toke.dk> <751EA059-654B-4E06-A3D6-C727FE1FCE98@gmx.de> <87lftjfz51.fsf@toke.dk> <18FC6F1D-084C-44BD-87E7-C9F394D6FCD1@gmx.de> <32a96b6ad48387876b7125adba147578564d297a.camel@sipsolutions.net> <661B8FD5-510B-4DC5-A080-F04CA1C10C71@gmx.de> <87imolc4p9.fsf@toke.dk> <87a79wd67g.fsf@toke.dk> To: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Mailer: Apple Mail (2.3445.104.11) X-Provags-ID: V03:K1:TD63kRtb0PCMY91JIrkbCBP6RjFY1Uaq3UD+0HA+tc+DTWkZgag 5rOr065aew9uUxS9mMxWDKkB5gnqqj8KpJpdMh+XmOJgvuK3yjmAnL/Vt94UMyQQWVtBvWy Mbul9DXVngCQwBkXpwdV+Q584DqSOX2wykS/z4xLmjmmvd5MR9Pj38nOKn7B5lZTf1AP0Z1 C0Vf8jhKjl62mwfBtL8rg== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:vJif6oyic+c=:r169oJvHdBfTZxF1L8LZ+X Mu6F59G86uHh0hbwEM8Ione7ZLRK7JUb7RQ85V2106/m80OyGY3a2WXMo45GmjcYf+qRueP4M 0pugXbwkqojbLQjV9U+GBa8FtGR0zVFYgia/zQ1fy6evO0yXv076pD2tuVHuCe6P+42z02dHV T3dKJAqsXLenwmDNSLB3pEhlkdmRgLvhDdbPCxyASVmyzQPBo/VjEoqTRZ9arQzLGHQgrhS6o 3ZPPyU2FL2L9p2+9mfQOfrvBRRdLukMuTUDSDsMDGSXHVOTpnoPQ5gDOoRvxkh1CmTDhSZrug X4bMpn3K4yazspiPaJPQh0Sy+lIlg4b6NuKyst8NN6BBSCijSA0bNHWsiuHpQf27fGhKCY9VD PSB5h8xATdQVjlw3l7N+N+jlkyKsdf0c/bSJjXZNwR9bwg7UkIQUM5XpZnrNx6yZfDwOqjCYa kNWBn+WC5cwzMkQ2IMx4rG4EXwUaSUq3qRV0PITqQp5LZBQZ7PDsBPm/5D2D3PWz7IlqamPfI JS02of4u7eAB2E28bQTD2QkQB4Fo2g9ShYnqn7Fg7MLuJfK3UDbXpxokHxcRbIEgviXPFe3Rd LXflOgL/Y1jmfQgazOGoB6ydJonAzQnA+MRu3pZ143xrZZBXSy5Rnw175/IHLzdUKmS+USprR UT35rrJ7NdjmtjGv8s7j8REXEGx+VZH/CqBpe8inNf963M2UZrWdkxZFcWIQSw5kEFemN5AAS ug213paZtWzMvOEXXs34rC8PN948lzN1NpmyBLiNhlumAzULn0U5B7zvwXMjG0EYFDh42XT3a HwtyGvMisth4LquoII0pXSiibP4AIvmnsFBfoUiBVaHwttZEFy1NTVG+xzEEjNr1dWNLYufd5 L2x5Qqhkbb/cRzI3X4Xe7U6+ckIzV4W7h6Gyb9+ZnEuXjh4Kcc5UpdmHIMVE2HB59GA8ChSi0 tHJ7m4xwf97Pj0ol4wgPMUlEwFMU1AQ/aDECCPSRL3FGfCW4BA4zExCDrabNxURCSMKvNJQfE +CnTtvn1YQJmbBbUD/yjQsijWYlTgq4EdJWaZNsjqT9MHhQNNOXAm7I+spDKxHmECV5iogss+ dGRDeT+6kONr2eYKVSAVGaPl5eYOY4KBUaPCxfcYPbP1sTzVzz4CsOFs0DZcRXaBTz4IbiWmQ w24Ldl1rI7o5xSXwT29VgaJNyIxs60q4f6ninmCGKJFHjd901hxH5akHfAuu7nIR41nwZNkas sbIgvnIaLn2d49kuYZk3LrV3ybT5kCC0IRcg8on7Ox2ZvFNKHTLQXIvd3oEc= Subject: Re: [Make-wifi-fast] [PATCH v2 4/4] mac80211: Use Airtime-based Queue Limits (AQL) on packet dequeue X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 19 Oct 2019 21:22:53 -0000 > On Oct 19, 2019, at 18:56, Toke H=C3=B8iland-J=C3=B8rgensen = wrote: >=20 > Sebastian Moeller writes: >=20 >> On October 19, 2019 2:14:42 PM GMT+02:00, "Toke H=C3=B8iland-J=C3=B8rge= nsen" wrote: >>> Sebastian Moeller writes: >>>=20 >>>>> On Oct 18, 2019, at 16:15, Johannes Berg = >>> wrote: >>>>>=20 >>>>> On Thu, 2019-10-17 at 18:11 -0700, Kan Yan wrote: >>>>>> I don't think it is hard to take care of extra header size for >>> frames >>>>>> with VLAN tags >>>>>=20 >>>>> VLAN tags are payload as far as wifi is concerned, so no need to >>> take >>>>> that into account ... >>>>=20 >>>> Ah, good to know; but just out of curiosity is any of the >>>> following 7 Byte Preamble + 1 Byte start of frame delimiter >>>> (SFD) + 12 Byte inter frame gap (IFG) actually packaged into >>>> ethernet frames inside 802.11 packets? I would have guessed that >>>> at least the IFG would be dropped as it does not really exist as >>>> "data"? >>>=20 >>> No, those are accounted in the airtime calculation in airtime.c = (Felix' >>> code). E.g.,: >>>=20 >>> duration =3D 20 + 16; /* premable + SIFS */ >>=20 >>=20 >> Looks like apples and pears to me. These seem to be the wifi preamble >> and short interframe space in microseconds. Sure you need to add = those >> to the airtime estimate as these will hog airtime. >>=20 >> But the 12 byte interframe gap of the Ethernet packets that are >> transmitted over a 802.11 link surely will not be actually = transmitted >> as a stretch of zeros? Same for the Ethernet preamble and the start = of >> frame marker, as those can/will be trivially added by the Ethernet = NIC >> that will handle the encapsulated Ethernet frame after the wifi link, >> no? >>=20 >> As far as I can tell, the wifi SIFS is constant time independent of >> wifi link speed while the IFG size is constant but it's duration is >> not? >>=20 >> Again, I am trying to understand this conceptually, which seems >> orthogonal to the question of whether 38 is the correct number.... >>=20 >> Best Regards >> Sebastian >>=20 >> P.S.: Is there a repository I could look into to try to figure this >> out myself? >=20 > This paper has a fairly comprehensive description of how frames look > when transmitted over the air: http://dx.doi.org/10.1155/2015/548109 > (see Figure 1 and Table 2, and the text in Section 2). >=20 > Otherwise you'll have to go read the standards, I guess (though I = can't > say I'd recommend it as light reading :P) >=20 Thanks! Well, that certainly was "fun", but as far as I can tell neither the = ethernet preamble, the Start of frame delimiter or the ethernet inter = frame gap will be actually transmitted/encapsulated over wifi; wifi will = use its own equivalents (in multiple versions) but these are seemingly = not guaranteed to have the same octet equivalents as their ethernet = counter parts. (Looking at the standard made my head slightly hurt and = looking at the massive overhead expansion wifi brings, I wonder why the = ethernet frame is not simply carried completely as payload... I guess = that is what WDS is doing, except for the "simple" part) Learned something new... ;) Regards Sebastian > -Toke