Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270672AbTHGUpX (ORCPT ); Thu, 7 Aug 2003 16:45:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270749AbTHGUpX (ORCPT ); Thu, 7 Aug 2003 16:45:23 -0400 Received: from holomorphy.com ([66.224.33.161]:14742 "EHLO holomorphy") by vger.kernel.org with ESMTP id S270672AbTHGUpW (ORCPT ); Thu, 7 Aug 2003 16:45:22 -0400 Date: Thu, 7 Aug 2003 13:45:59 -0700 From: William Lee Irwin III To: Daniel Phillips Cc: rob@landley.net, Ed Sweetman , Eugene Teo , LKML , kernel@kolivas.org, Davide Libenzi Subject: Re: Ingo Molnar and Con Kolivas 2.6 scheduler patches Message-ID: <20030807204559.GY32488@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Daniel Phillips , rob@landley.net, Ed Sweetman , Eugene Teo , LKML , kernel@kolivas.org, Davide Libenzi References: <1059211833.576.13.camel@teapot.felipe-alfaro.com> <200307271046.30318.phillips@arcor.de> <200308061728.04447.rob@landley.net> <200308071642.55517.phillips@arcor.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200308071642.55517.phillips@arcor.de> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1336 Lines: 27 On Wednesday 06 August 2003 22:28, Rob Landley wrote: >> So, how does SCHED_SOFTRR fail? Theoretically there is a minimum timeslice >> you can hand out, yes? And an upper bound on scheduling latency. So >> logically, there is some maximum number "N" of SCHED_SOFTRR tasks running >> at once where you wind up round-robining with minimal timeslices and the >> system is saturated. At N+1, you fall over. (And in reality, there are >> interrupts and kernel threads and other things going on that get kind of >> cramped somewhere below N.) On Thu, Aug 07, 2003 at 04:42:55PM +0100, Daniel Phillips wrote: > The upper bound for softrr realtime scheduling isn't based on number > of tasks, it's a global slice of cpu time: so long as the sum of > running times of all softrr tasks in the system lies below limit, > softrr tasks will be scheduled as SCHED_RR, otherwise they will be > SCHED_NORMAL. You're thinking of Little's law, which is describes the mean number of waiters on a queue as the mean service time divided by the number of servers times the mean inter-arrival time. -- wli - 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/