Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262530AbVBCCzF (ORCPT ); Wed, 2 Feb 2005 21:55:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262563AbVBCCzE (ORCPT ); Wed, 2 Feb 2005 21:55:04 -0500 Received: from smtp.Lynuxworks.com ([207.21.185.24]:43014 "EHLO smtp.lynuxworks.com") by vger.kernel.org with ESMTP id S262484AbVBCCyf (ORCPT ); Wed, 2 Feb 2005 21:54:35 -0500 Date: Wed, 2 Feb 2005 18:54:07 -0800 To: Peter Williams Cc: "Bill Huey (hui)" , "Jack O'Quin" , Ingo Molnar , Nick Piggin , Paul Davis , Con Kolivas , linux , rlrevell@joe-job.com, CK Kernel , utz , Andrew Morton , alexn@dsv.su.se, Rui Nuno Capela , Chris Wright , Arjan van de Ven Subject: Re: [patch, 2.6.11-rc2] sched: RLIMIT_RT_CPU_RATIO feature Message-ID: <20050203025407.GB15334@nietzsche.lynx.com> References: <20050126070404.GA27280@elte.hu> <87fz0neshg.fsf@sulphur.joq.us> <1106782165.5158.15.camel@npiggin-nld.site> <874qh3bo1u.fsf@sulphur.joq.us> <1106796360.5158.39.camel@npiggin-nld.site> <87pszr1mi1.fsf@sulphur.joq.us> <20050127113530.GA30422@elte.hu> <873bwfo8br.fsf@sulphur.joq.us> <20050202111045.GA12155@nietzsche.lynx.com> <42014C10.60407@bigpond.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42014C10.60407@bigpond.net.au> User-Agent: Mutt/1.5.6+20040907i From: Bill Huey (hui) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1600 Lines: 31 On Thu, Feb 03, 2005 at 08:54:24AM +1100, Peter Williams wrote: > As Ingo said in an earlier a post, with a little ingenuity this problem > can be solved in user space. The programs in question can be setuid > root so that they can set RT scheduling policy BUT have their > permissions set so that they only executable by owner and group with the > group set to a group that only contains those users that have permission > to run this program in RT mode. If you wish to allow other users to run > the program but not in RT mode then you would need two copies of the > program: one set up as above and the other with normal permissions. Again, in my post that you snipped you didn't either read or understand what I was saying regarding QoS, nor about the large scale issues regarding dual/single kernel development environments. Ultimately this stuff requires non-trivial support in kernel space, a softirq thread migration mechanism and a frame driven scheduler to back IO submission across async boundaries. My posts where pretty clear on this topic and lot of this has origins coming from SGI IRIX. Yes, SGI IRIX. One of the only system man enough to handle this stuff. Ancient, antiquated Unix scheduler semantics (sort and run) and lack of control over critical facilities like softirq processing are obstacles to getting at this. bill - 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/