From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-x22a.google.com (mail-io0-x22a.google.com [IPv6:2607:f8b0:4001:c06::22a]) (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 5AC213B260 for ; Tue, 22 Nov 2016 13:34:28 -0500 (EST) Received: by mail-io0-x22a.google.com with SMTP id j65so75398690iof.0 for ; Tue, 22 Nov 2016 10:34:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=cb30eF7X1lfLKwJpl+kEUeuEHAHDHvjn1kf1Hl2SMJI=; b=ZTxtseI+hzJSVQ79o67iWVnPFWpkLFX/fkIX8F3xsIQ/B/Q0kVWfWVWblhr4zdIfaw nPSg3VzonvAtay76gHMWcUGhpuFx5oULSeBElKyF97oi1+TIbCNQqfDMMhWx2HrJi6i3 69E3bbROgt4r2fFxXY6FmXL7Ii3W1xevuCYnlqzdHxi4E2mx+q73qZ9bEOu9cUWIsEvT ndlGI6mL9pVWJSBSTBLVhQ8UI9gUjUwxCJzup+Qh/qPJBzu9t0NhGH1vca/j5dKSO8jj eDPlppzZ2WnOpYumPc5G3GZi/LsTIgvAugI2Q4b+M/2NMTIHThJA7uEM9yJ6XNhqPSfA umFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=cb30eF7X1lfLKwJpl+kEUeuEHAHDHvjn1kf1Hl2SMJI=; b=QxAlI9SoYRHmj0RxRcWb8Wm51Q8mt2YX8EeCVgKJIsftyPs6jUXtLbrpe/inMGnSzH nnnZXjuGeD4QOyxBGI4Qojahj5PO1ocKK2s2IcB7BKdPEMF/Gr1ChAXoCeuw7Yyx1mV8 PiYAxqHJr89IqlOIec9zYhN1Q7yulMJhCqAGuPUodc2o8bhPejiI7ngHxX28lkV44jPJ mmcIOppQigVfDsmDHg/Xu2k+pYod/XLrtu/gsB5LJK1WzdajAAlOrsDQQCsEawK/KVEL WnC2nT6zBJIYxDMvwnL9uN8XFq1iPLfYHUr7BP8YxMJcKqClfZmcB0bvVNV5BVASy8WG D0pQ== X-Gm-Message-State: AKaTC00SZv6c0sCYCJJUmIvdMq2IAPiX+cRdS1gafarZ0Ne41l1d2SQEvvSS2mrOxBZTCTBgOvOWvuk8EDE32A== X-Received: by 10.36.66.143 with SMTP id i137mr3799924itb.43.1479839667708; Tue, 22 Nov 2016 10:34:27 -0800 (PST) MIME-Version: 1.0 Received: by 10.50.12.234 with HTTP; Tue, 22 Nov 2016 10:34:27 -0800 (PST) In-Reply-To: <97DE7A30-F225-4B9C-B84B-DD3C38F35A69@gmail.com> References: <97DE7A30-F225-4B9C-B84B-DD3C38F35A69@gmail.com> From: Loganaden Velvindron Date: Tue, 22 Nov 2016 22:34:27 +0400 Message-ID: To: Jonathan Morton Cc: make-wifi-fast@lists.bufferbloat.net Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Make-wifi-fast] 3g/4g with fq_codel & mobility 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: Tue, 22 Nov 2016 18:34:28 -0000 On Mon, Nov 21, 2016 at 3:27 PM, Jonathan Morton wr= ote: > >> On 21 Nov, 2016, at 13:16, Loganaden Velvindron wr= ote: >> >> I have one of those gl.inet 6416a board. It runs fq_codel on the >> USB-3g dongle modem interface, and it runs very well at rest. >> >> I put it inside a car, and while driving, I notice some induced latency: >> >> https://www.dslreports.com/speedtest/6354936 >> >> Can someone who has some understanding of 3g/4g internals shed some >> light ? Could the 3g/4g modem be buffering due to varying strength of >> the signal or due to handover in base station ? > > Usually such dongles don=E2=80=99t give direct access to the 3G modem int= erface. Instead they provide an Ethernet or PPP interface, and do a conver= sion internally. Ethernet emulation is more common of late, possibly due t= o the rise of 4G. > > Running fq_codel on such a device without a shaper relies on the buffers = in *both* the dongle itself and the driver for the emulated Ethernet device= having appropriately sized buffers in aggregate. This is virtually never = the case. And that=E2=80=99s just for the upload direction. > > In the download direction you are relying on buffers in the provider=E2= =80=99s network and the cell tower. Fq_codel on your own hardware has no e= ffect here. > I think that reducing the buffer size with NCM might be a good start, particularly with 4G. THere is a lot of work to be done on the USB-ethernet stack.