From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-x241.google.com (mail-oi0-x241.google.com [IPv6:2607:f8b0:4003:c06::241]) (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 B3CB43B2A0 for ; Fri, 17 Jun 2016 23:40:52 -0400 (EDT) Received: by mail-oi0-x241.google.com with SMTP id d132so16821299oig.3 for ; Fri, 17 Jun 2016 20:40:52 -0700 (PDT) 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; bh=+7ZcljVopz16VvHo++g/oLYe2ObAzyjA1U1vrHSQWp4=; b=pyDYQJnkSR+E0U1TSjkeRQ16vXehEiV0objLk/DMlFp24pTQ8/Wz5cRREGTWeeVc1f UgV6q1pXPBepVMWBoTxf2aWvHaBh3/xC7kC0lLzXbeTqVxIipfdiU+0EvP5r/lO4vzQo yKmCK3CCN20LqyPlnMqxXUcmh7N1jTdsibhtNlFjandBkmBRUwHJUWL/BBR2yycZCgz9 HYqTXQuUFQsGP6wFsuXwnoFgnOZYabDj+x9YcLwCnKF03SKi97vnmJLGo0EebuOv81bq Wej0J5Ozta0B/q3pDYG7JkBgmnsBabu7qhfMqmhXb1B646O/am4+cAfkZeOc8o994JKj 5ceQ== 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; bh=+7ZcljVopz16VvHo++g/oLYe2ObAzyjA1U1vrHSQWp4=; b=kR/1fRGUbus65un7nN9VBn8sQLvAikO8VNJVUoCG99cbcdNHIHYb+oeszBs54WxWnH OOrSELhGcTDwPiwDmTwqQXHoU4psclcoIYH4lgjFLr2lF0Ipzws1geh2r2n3vyfvb5jZ oo/8NX5OonC0iD4jYvkO49pGDadbJygmOzoWCKQfo7YAPrmLncO09PDpOUzGlxXPoTGe 2blXQuktCG8Ljj2zGraT8EcHjcLZCb09llfpsrx/Qk9QwjmlKf13dB/oJGQKqCUdCTmT Qn0vGdKt/ivzpiLTiS0CZzkjuxmZMTbf0kio3qpYUASUIT39xHGE5HhjaNyVemTajVan JLwg== X-Gm-Message-State: ALyK8tLQYhPnBc78tRW6eZRILNynZI9lrpDTvcv83ZS4lM99O9QlF+cDgLjoFqbI0XNLJuuXr+61jpmHnRE0Eg== X-Received: by 10.202.214.86 with SMTP id n83mr3365553oig.66.1466221252127; Fri, 17 Jun 2016 20:40:52 -0700 (PDT) MIME-Version: 1.0 Received: by 10.202.175.130 with HTTP; Fri, 17 Jun 2016 20:40:51 -0700 (PDT) In-Reply-To: <0D81073C-4F45-40E4-84CD-CC61BF8001A7@gmail.com> References: <548a7871-e2b9-4802-3508-e57f34368096@gmail.com> <0D81073C-4F45-40E4-84CD-CC61BF8001A7@gmail.com> From: Dave Taht Date: Fri, 17 Jun 2016 20:40:51 -0700 Message-ID: To: Jonathan Morton Cc: Noah Causin , bloat Content-Type: text/plain; charset=UTF-8 Subject: Re: [Bloat] USB Ethernet Adapters with BQL? X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 18 Jun 2016 03:40:52 -0000 most usb network adaptors tend to use the "usbnet" infrastructure, which tries to minimize interrupts, but also tends towards trying to only keep 5ms or so of data "in flight", so leveraging fq_codel on top of a usb ethernet device at the qdisc layer tends to show a small, but measurable benefit, at 100 mbit or a gbit. We tend to run out of speed of the bus on usb2 for gbit. this is not quite true on slow things like the raspberry pi1, where we run out of cpu first. somewhere around here I have benchmarks of this sort of usb stuff on various platforms, but in the end the results were reasonable enough (latency/jitter less than 20ms typically) for me to not stress out about it. Please feel free to try a comparison between pfifo_fast and fq_codel on top of a given usb-ethernet device. ... the infrastructure for usb 3G modems is a whole other ball of wax. It is a more or less mandated part of the standards that at least 32k exist on the other side of the device and the underlying code was pretty overbuffered too (and 3G can get well below a mbit on uploads).... I have longed for something bql-like there. usb-wifi also tends towards utterly horrific. ... I also am using usb "gadget ethernet" drivers with some success on the getchip and beaglebone, with mildly better results for fq_codel over pfifo_fast. The getchip does not have fq_codel yet, however, and they had a bit of trouble getting the combined cdc/serial ethernet gadget to work on their latest kernel release. (aside from being in a losing battle currently with systemd on device renaming - usb gadget ethernet works great with openwrt).