From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262235AbVAUCii (ORCPT ); Thu, 20 Jan 2005 21:38:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262237AbVAUCih (ORCPT ); Thu, 20 Jan 2005 21:38:37 -0500 Received: from gizmo04bw.bigpond.com ([144.140.70.14]:40647 "HELO gizmo04bw.bigpond.com") by vger.kernel.org with SMTP id S262235AbVAUCie (ORCPT ); Thu, 20 Jan 2005 21:38:34 -0500 Message-ID: <41F06B26.6000702@bigpond.net.au> Date: Fri, 21 Jan 2005 13:38:30 +1100 From: Peter Williams User-Agent: Mozilla Thunderbird 0.9 (X11/20041127) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Marc E. Fiuczynski" CC: Linux Kernel Mailing List , Con Kolivas , Chris Han , ckrm-tech@lists.sourceforge.net Subject: Re: [ANNOUNCE][RFC] plugsched-2.0 patches ... References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Marc E. Fiuczynski wrote: > Peter, thank you for maintaining Con's plugsched code in light of Linus' and > Ingo's prior objections to this idea. On the one hand, I partially agree > with Linus&Ingo's prior views that when there is only one scheduler that the > rest of the world + dog will focus on making it better. On the other hand, > having a clean framework that lets developers in a clean way plug in new > schedulers is quite useful. > > Linus & Ingo, it would be good to have an indepth discussion on this topic. > I'd argue that the Linux kernel NEEDS a clean pluggable scheduling > framework. > > Let me make a case for this NEED by example. Ingo's scheduler belongs to > the egalitarian regime of schedulers that do a poor job of isolating > workloads from each other in multiprogrammed environments such as those > found on Enterprise servers and in my case on PlanetLab (www.planet-lab.org) > nodes. This has been rectified by HP-UX, Solaris, and AIX through the use > of fair share schedulers that use O(1) schedulers within a share. Currently > PlanetLab uses a CKRM modified version of Ingo's scheduler. I'm hoping that the CKRM folks will send me a patch to add their scheduler to plugsched :-) > Similarly, the > linux-vserver project also modifies Ingo's scheduler to construct an > entitlement based scheduling regime. These are not just variants of O(1) > schedulers in the sense of Con's staircase O(1). Nor is it clear what the > best type of scheduler is for these environments (i.e., HP-UX, Solaris and > AIX don't have it fully solved yet either). The ability to dynamically swap > out schedulers on a production system like PlanetLab would help in > determining what type of scheduler is the most appropriate. This is because > it is non-trivial, if not impossible, to recreate the multiprogrammed > workloads that we see in a lab. > > For these reasons, it would be useful for plugsched (or something like it) > to make its way into the mainline kernel as a framework to plug in different > schedulers. Alternatively, it would be useful to consider in what way > Ingo's scheduler needs to support plugins such as the CKRM and Vserver types > of changes. > > Best regards, > Marc -- Peter Williams pwil3058@bigpond.net.au "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce