From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751433AbZHZOyM (ORCPT ); Wed, 26 Aug 2009 10:54:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751266AbZHZOyK (ORCPT ); Wed, 26 Aug 2009 10:54:10 -0400 Received: from mail-bw0-f219.google.com ([209.85.218.219]:35857 "EHLO mail-bw0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750981AbZHZOyH (ORCPT ); Wed, 26 Aug 2009 10:54:07 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=ktiya2nzjPeB93aW8dLmTotcbQm6WzssYp9hcJE9ZEEEeF4S8YhErbD8OFtvqFwidG EvnoT7ELREWJbnkzyA59fzq9H5+eHw3OzsaiOqTny41IKLKhEN0OG2cVrO/kDU5fUtQC UI7Vm/hv5rUgTbtWl7tMIyTrwXHAd9/d7t4yE= Subject: Re: RFC: THE OFFLINE SCHEDULER From: raz ben yehuda To: Maxim Levitsky Cc: Christoph Lameter , Peter Zijlstra , Chris Friesen , Mike Galbraith , riel@redhat.com, mingo@elte.hu, andrew motron , wiseman@macs.biu.ac.il, lkml , linux-rt-users@vger.kernel.org In-Reply-To: <1251297910.1791.22.camel@maxim-laptop> References: <1250983671.5688.21.camel@raz> <1251004897.7043.70.camel@marge.simson.net> <1251018551.3810.35.camel@raz> <1251012621.14003.71.camel@marge.simson.net> <1251025557.3810.65.camel@raz> <1251021133.14003.172.camel@marge.simson.net> <1251222993.7023.53.camel@marge.simson.net> <1251227322.7538.1172.camel@twins> <4A943A00.9080609@nortel.com> <1251264700.7538.1178.camel@twins> <1251282598.3514.20.camel@raz> <1251297910.1791.22.camel@maxim-laptop> Content-Type: text/plain Date: Wed, 26 Aug 2009 17:54:03 +0300 Message-Id: <1251298443.4791.7.camel@raz> Mime-Version: 1.0 X-Mailer: Evolution 2.12.3 (2.12.3-8.el5_2.3) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2009-08-26 at 17:45 +0300, Maxim Levitsky wrote: > On Wed, 2009-08-26 at 09:47 -0400, Christoph Lameter wrote: > > On Wed, 26 Aug 2009, raz ben yehuda wrote: > > > > > How will the kernel is going to handle 32 processors machines ? These > > > numbers are no longer a science-fiction. > > > > The kernel is already running on 4096 processor machines. Dont worry about > > that. > > > > > What i am suggesting is merely a different approach of how to handle > > > multiple core systems. instead of thinking in processes, threads and so > > > on i am thinking in services. Why not take a processor and define this > > > processor to do just firewalling ? encryption ? routing ? transmission ? > > > video processing... and so on... > > > > I think that is a valuable avenue to explore. What we do so far is > > treating each processor equally. Dedicating a processor has benefits in > > terms of cache hotness and limits OS noise. > > > > Most of the large processor configurations already partition the system > > using cpusets in order to limit the disturbance by OS processing. A set of > > cpus is used for OS activities and system daemons are put into that set. > > But what can be done is limited because the OS threads as well as > > interrupt and timer processing etc cannot currently be moved. The ideas > > that you are proposing are particularly usedful for applications that > > require low latencies and cannot tolerate OS noise easily (Infiniband MPI > > base jobs f.e.) > > My 0.2 cents: > > I have always been fascinated by the idea of controlling another cpu > from the main CPU. > > Usually these cpus are custom, run proprietary software, and have no > datasheet on their I/O interfaces. > > But, being able to turn an ordinary CPU into something like that seems > to be very nice. > > For example, It might help with profiling. Think about a program that > can run uninterrupted how much it wants. > > I might even be better, if the dedicated CPU would use a predefined > reserved memory range (I wish there was a way to actually lock it to > that range) > > On the other hand, I could see this as a jump platform for more > proprietary code, something like that: we use linux in out server > platform, but out "insert buzzword here" network stack pro+ can handle > 100% more load that linux does, and it runs on a dedicated core.... > > In the other words, we might see 'firmwares' that take an entire cpu for > their usage. This is exactly what offsched (sos) is. you got it. SOS was partly inspired by the notion of a GPU. Processors are to become more and more redundant and Linux as an evolutionary system must use it. why not offload raid5 write engine ? why not encrypt in a different processor ? Also , having so many processors in a single OS means a bug prone system , with endless contention points when two or more OS processors interacts. let's make things simpler. > > > > > > -- > > 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/ >