From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261536AbVFEIzA (ORCPT ); Sun, 5 Jun 2005 04:55:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261537AbVFEIzA (ORCPT ); Sun, 5 Jun 2005 04:55:00 -0400 Received: from mx2.elte.hu ([157.181.151.9]:22670 "EHLO mx2.elte.hu") by vger.kernel.org with ESMTP id S261536AbVFEIyr (ORCPT ); Sun, 5 Jun 2005 04:54:47 -0400 Date: Sun, 5 Jun 2005 10:53:13 +0200 From: Ingo Molnar To: Esben Nielsen Cc: Thomas Gleixner , linux-kernel@vger.kernel.org, Inaky Perez-Gonzalez , Daniel Walker , Oleg Nesterov Subject: Re: patch] Real-Time Preemption, plist fixes Message-ID: <20050605085313.GA30946@elte.hu> References: <1117958706.20785.243.camel@tglx.tec.linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Esben Nielsen wrote: > When K is a constant or bounded by a constant (140 in this > application) any function which is O(K) is O(1) per definition of O! technically you are right. But the question is - while K is considered a constant, and N (nr_running_RT_tasks) is technically not bounded - in practice N is bounded just as much. Have you ever seen any hard-RT application that has more than 140 threads _running at the same time_ on a single CPU? You can even enforce it to be theoretically bounded, via ulimits. in fact, K and N should be pretty close to each other for most applications. I'd be interested in real application scenarios where N is much (== more than 10 times) larger than K and plists really matter. Ingo