From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753813AbaFNUdy (ORCPT ); Sat, 14 Jun 2014 16:33:54 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:44845 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753612AbaFNUdw (ORCPT ); Sat, 14 Jun 2014 16:33:52 -0400 Date: Sat, 14 Jun 2014 22:33:26 +0200 From: Pavel Machek To: Cong Wang Cc: Josh Triplett , David Miller , Andi Kleen , Linux Kernel Network Developers , LKML , tom.zanussi@linux.intel.com, Andi Kleen Subject: Re: [PATCH 08/24] net, diet: Make TCP metrics optional Message-ID: <20140614203326.GC3853@xo-6d-61-c0.localdomain> References: <20140506155703.GA20391@cloud> <20140506.115941.428706504757835279.davem@davemloft.net> <20140506164108.GA20536@cloud> <20140506.131643.994244006906866938.davem@davemloft.net> <20140506175547.GE20776@cloud> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 2014-05-06 11:33:11, Cong Wang wrote: > On Tue, May 6, 2014 at 10:55 AM, wrote: > > On Tue, May 06, 2014 at 01:16:43PM -0400, David Miller wrote: > >> From: josh@joshtriplett.org > >> Date: Tue, 6 May 2014 09:41:08 -0700 > >> > >> > Every KB of RAM costs real money and SoC die area (for eDRAM/eSRAM). > >> > >> Another poster commented that 16MB of DRAM would be cheaper than > >> the 2MB of ram you have on these boards, probably one that fits > >> your size profile is available as well. > >> > >> 2MB is just a rediculous restriction. > > > > Embedded systems experts disagree with you there; there *are* systems > > where the most cost-efficient approach is a few MB (or a few hundred KB) > > of non-discrete memory. We're not talking about socketed memory or even > > soldered-down memory; we're talking about entire systems that fit on a > > small SoC die. The space not used by that extra RAM may well be better > > spent on CPU optimizations, or some other integrated component. > > > > Such boards will be built, and many of them will run Linux, despite your > > incredulity. When you're building millions of a board, it's well worth > > optimizing software to eliminate components from the bill of materials. > > So why bothers 3.15+ Linux kernel? Why not use an old kernel e.g. 2.4.x? > 2.4.x kernel doesn't have so many new features you want to get rid of here. So.. what is kernel composed of? Ton of drivers and a bit of generic code. And when doing this, you probably need the drivers from 3.x for your hardware. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html