Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 20 Jun 2002 17:59:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 20 Jun 2002 17:59:24 -0400 Received: from [195.63.194.11] ([195.63.194.11]:56070 "EHLO mail.stock-world.de") by vger.kernel.org with ESMTP id convert rfc822-to-8bit; Thu, 20 Jun 2002 17:59:23 -0400 Message-ID: <3D125032.3040809@evision-ventures.com> Date: Thu, 20 Jun 2002 23:59:14 +0200 From: Martin Dalecki User-Agent: Mozilla/5.0 (X11; U; Linux i686; pl-PL; rv:1.0.0) Gecko/20020611 X-Accept-Language: pl, en-us MIME-Version: 1.0 To: Linus Torvalds CC: Cort Dougan , "Eric W. Biederman" , Benjamin LaHaise , Rusty Russell , Robert Love , Linux Kernel Mailing List Subject: Re: latest linus-2.5 BK broken References: Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3804 Lines: 95 U?ytkownik Linus Torvalds napisa?: > > On Thu, 20 Jun 2002, Martin Dalecki wrote: > >>Linus you forget one simple fact - a HT CPU is *not* two CPUs. >>It is one CPU with a slightly better utilization of the >>super scalar pipelines. > > > Doesn't matter. It's SMP to software, _and_ it is a perfect example of how > integration, in the form of almost free transistors, changes the > economics. Well but this simply still doesn't make SMP magically scale better. HT gives you about 12% increase in throughput on average. This will hardly increase your MP3 ripping expierence :-). > Integration is _not_ "just another way". > > Integration fundamentally changes the whole equation. > > When you integrate the SMP capabilities on the CPU, suddenly the world > changes, because suddenly SMP is cheap and easy to do for motherboard > manufacturers that would never have done it before. Suddenly SMP is > available at mass-market prices. And suddenly the Chip-Set manufacturers start to buy CPU designs like creazy, becouse they can see what will be next... of course. > When you integrate multiple CPU's on one standard die (either HT or real > CPU's), the same thing happens. Again HT is still only one CPU. You are too software centric :-). > When you start integrating crossbars etc "numa-like" stuff, like Hammer > apparently is doing, you get the same old technology, but it _behaves_ > differently. Yes HT gives 12%. naive SMP gives 50% and good SMP (aka corssbar bus) gives 70% for two CPU. All those numbers are well below the level where more then 2-4 makes hardly any sense... Amdahl bites you still if you read it like: 88% waste (well actuall this time not) 50% waste 20% waste on scale. However corssbar switches are indeed allowing for maximally 64 CPUs and more importantly it's the first step since a long time to provide better overall system throughput. However they will still not be near any commodity - too much heat for the foreseeable future. > You see this outside CPU's too. > > When people started integrating high-performance 3D onto a single die, the > _market_ changed. The way people used it changed. It's largely the same > technology that has been around for a long time in visual workstations, > but it's DIFFERENT thanks to low prices and easy integration into > bog-standard PC's. > > A 3D tech person might say that the technology is still the same. > > But a real human will notice that it's radically different. Yes but you can drive the technology only up to the perceptual limits of a human. For example since about 6 years all those advancements in the graphics area are largely uninterresting to me. I don't play computer games. Never - they are too boring. Jet another fan in my computer - no thank's. > Did you mention that there are a lot more resistors in computers than > CPU's? No. It is irrelevant. It doesn't drive technology in fundamental > ways - even though the amount of fundamental technolgy inherent on a > modern motherboard in _just_ the passive components like the resistor > network is way beyond what people built just a few years ago. Well the last real technological jump comparable to the invention of television was actually due to this kind of CPUs which you compare to microbes - mobiles :-). And well I'm awaiting the day where there will be some WinWLAN card as shoddy as those Win modems are... Fortunately they made 802.11b complicated enough :-) But with a corssbar switch in place they could well make up for the latency on the main CPU... oh fear... oh scare... - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/