From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from uplift.swm.pp.se (swm.pp.se [212.247.200.143]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 1D6603B25E for ; Fri, 30 Sep 2016 04:12:22 -0400 (EDT) Received: by uplift.swm.pp.se (Postfix, from userid 501) id 8FB43A2; Fri, 30 Sep 2016 10:12:20 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=swm.pp.se; s=mail; t=1475223140; bh=CNFGA6DEOY4m4yw3BsPS5E4o5RQix+5iLfXcPV0p1DU=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=Xl7t372EgOzvj8eNx7JjM/GOTGnUP7T6WD1NgLLaaV+Gw9DYobdisC4RTMOEjvmxg G7vE9BjKvKzLHGzmt6gzcpyaGASM035c/03DIKmoxZQZD7hKNrsgfP/Wg/6/r+o//J XuJU1kEcipXoYniZV8CtxVIDFVhLifB5IHTsUNpU= Received: from localhost (localhost [127.0.0.1]) by uplift.swm.pp.se (Postfix) with ESMTP id 85AC5A1; Fri, 30 Sep 2016 10:12:20 +0200 (CEST) Date: Fri, 30 Sep 2016 10:12:20 +0200 (CEST) From: Mikael Abrahamsson To: Aaron Wood cc: =?ISO-8859-15?Q?Dave_T=E4ht?= , bloat In-Reply-To: Message-ID: References: <20160916211120.GA38308@sesse.net> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) Organization: People's Front Against WWW MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Subject: Re: [Bloat] "BBR" TCP patches submitted to linux kernel 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: Fri, 30 Sep 2016 08:12:22 -0000 On Thu, 29 Sep 2016, Aaron Wood wrote: > While you think 3.10 is old, in my experience it's still seen as cutting > edge by many. RHEL is still only at 3.10. And routers are using much > older 3.x kernels. There's a huge lag between what the "enterprise" > crowd is running in production, and what you guys are developing on. > Because "stability". > > It's been one of my major frustrations (especially on the embedded side > where 3.x kernels are still considered 'new' and 2.6.x is 'trusted'). State of affairs are actually improving. What I'm seeing from several SoC vendors is that they're moving from a "new kernel every 3 years, and we'll choose a 2 year old kernel when doing the work so it'll be 5 years old by the time a new one comes around, with the result that a lot of devices are on 2.6.26, 3.2 and 3.4), to a model where they actually do a new kernel every 6 months, and they'll choose a kernel that's around 12-18 months old at that time. This is of course not great, but it's an improvement. I'm pushing for SoC vendors to actually upstream their patches as much as possible and support creation of kernel version independent HAL/API in the kernel that they can write their drivers for. So if you know any netdev people, please tell them to be supportive when SoC vendors come and want changes done to the kernel to support for instance hw packet accelerators. We want this done right of course (so we can live with it for the next 5-10 years at least), but this is very important that it gets done. This of course has interesting effects for AQM, since with packet accelerators you're taking the kernel pretty much out of the data path as soon as the hardware is programmed... but that's a different but related struggle to make sure that these aren't as bloated as yesteryears implementations. -- Mikael Abrahamsson email: swmike@swm.pp.se