From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxim Levitsky Subject: Re: RFC: THE OFFLINE SCHEDULER Date: Wed, 26 Aug 2009 17:45:10 +0300 Message-ID: <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> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: raz ben yehuda , 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 To: Christoph Lameter Return-path: Received: from mail-fx0-f217.google.com ([209.85.220.217]:36894 "EHLO mail-fx0-f217.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750802AbZHZOpP (ORCPT ); Wed, 26 Aug 2009 10:45:15 -0400 In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: 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. > > > -- > 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/