From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f181.google.com (mail-wi0-f181.google.com [209.85.212.181]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 5956B20099A; Sat, 18 Aug 2012 11:53:08 -0700 (PDT) Received: by wibhm2 with SMTP id hm2so2021487wib.10 for ; Sat, 18 Aug 2012 11:53:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; bh=mVx2/+I302UxWKhwntWLtWnC5Ny12Cj7BdoBizbX5Js=; b=yQr4X66FrmkxPgOjG1bIoB1L8bEqaOs1CDL2vuZ0cwH+k988UKh90deyQukGNuJCiQ txtx2xXX1yXIp5dgnk3kc/0sAlWKIAbKbgpRfkp9HhB8gJPlU79kfd9ut6H0QTdNVFIX +OOLUXmrXta4O87VPje51komsMoXY4lmON3RXlFgIiVAuJmyt5FZz8JLW9dLDVztClE3 ctas9r4tFZIJnvMCJeJV6wxaQ9WLLXJSjyshgmQ/cm3dIQ0Ifg7MMjH7zQZDdpxMXj4+ bnkHRnGKyqOOGDtIrGK5YyOL5tR6AIpO5aiO0meMZ1QzJYicre9rKvDAAmWmITcVpw/f daIg== MIME-Version: 1.0 Received: by 10.180.78.170 with SMTP id c10mr14789147wix.3.1345315986424; Sat, 18 Aug 2012 11:53:06 -0700 (PDT) Received: by 10.223.143.69 with HTTP; Sat, 18 Aug 2012 11:53:06 -0700 (PDT) In-Reply-To: <502FD9EA.6070009@gmail.com> References: <502F2FA3.1000004@renta.net> <502FD9EA.6070009@gmail.com> Date: Sat, 18 Aug 2012 11:53:06 -0700 Message-ID: Subject: Re: [Cerowrt-devel] Raspberry Pi build From: Dave Taht To: Robert Bradley Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: bloat-devel , cerowrt-devel@lists.bufferbloat.net X-BeenThere: bloat-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: "Developers working on AQM, device drivers, and networking stacks" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 18 Aug 2012 18:53:08 -0000 On Sat, Aug 18, 2012 at 11:07 AM, Robert Bradley wrote: > On 18/08/12 18:38, Dave Taht wrote: >> >> 2) I have no idea what wireless chip is in the pi, nor its current state= . >> (?) > > > The Raspberry Pi has no built-in wireless chip, but using USB WiFi adapte= rs > would be possible. > >> 3) In order for things like fq_codel to have a hope of working well at >> the ethernet level, "Byte Queue Limits" (BQL) is *required*. I don't >> think any USB to ethernet adaptors have that yet, but I would welcome >> being wrong. And even if BQL worked over USB, we might have issues >> with the USB layer left to deal with... but BQL is easy to implement >> on native ethernet (6-8 lines of code or so)... >> >> I went looking through the source trees briefly and didn't find >> anything that jumped out at me. If you can point me to the right >> drivers I'll take a look. (and/or ask question 3 on a rasperry pi list >> for us?) >> > > I did a bit of digging, and the Raspberry Pi uses the SMSC LAN9512 chip f= or > wired Ethernet > (http://www.smsc.com/media/Downloads_Public/Data_Sheets/9512.pdf). The > smsc95xx driver currently lacks BQL support, so that would need to be add= ed > first. 22k worth of native buffering in the driver (at least at this layer) (at 100Mbit, I usually use 3k) #define DEFAULT_HS_BURST_CAP_SIZE (16 * 1024 + 5 * HS_USB_PKT_SIZE) #define DEFAULT_FS_BURST_CAP_SIZE (6 * 1024 + 33 * FS_USB_PKT_SIZE) And: Either this is a "yea! one abstraction to fit them all", or a "oh, god, we need something else to track completions", as above it uses a generic usbnet.c driver, which, sigh, does try to aggregate too. Interestingly it tries to live for 5ms at a time, interrupt-free. This is worrisome given codel at the layer its at and its 5ms target. Also wandering through the various conditions in tx_complete was "interesti= ng" I kind of wish I hadn't looked! But for all I know this is a simpler use-case for addressing aggregated packets than wifi... > > -- > Robert Bradley > > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel --=20 Dave T=E4ht http://www.bufferbloat.net/projects/cerowrt/wiki - "3.3.8-17 is out with fq_codel!"