From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753878AbXDNRys (ORCPT ); Sat, 14 Apr 2007 13:54:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754174AbXDNRys (ORCPT ); Sat, 14 Apr 2007 13:54:48 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:60184 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753878AbXDNRyr (ORCPT ); Sat, 14 Apr 2007 13:54:47 -0400 Date: Sat, 14 Apr 2007 19:54:33 +0200 From: Ingo Molnar To: "Eric W. Biederman" Cc: Willy Tarreau , Nick Piggin , linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Con Kolivas , Mike Galbraith , Arjan van de Ven , Thomas Gleixner , Jiri Slaby , Alan Cox Subject: Re: [Announce] [patch] Modular Scheduler Core and Completely Fair Scheduler [CFS] Message-ID: <20070414175433.GA17527@elte.hu> References: <20070414064334.GA19463@elte.hu> <20070414080833.GL943@1wt.eu> <20070414083625.GM943@1wt.eu> <20070414105338.GB19454@elte.hu> <20070414130101.GA2538@1wt.eu> <20070414132732.GA22103@1wt.eu> <20070414161927.GD3099@elte.hu> <20070414172920.GA2433@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Eric W. Biederman wrote: > > Thinking about it, I don't know if there are calls to schedule() > > while switching from tty1 to tty2. Alt-F2 had no effect anymore, and > > "chvt 2" simply blocked. It would have been possible that a > > schedule() call somewhere got starved due to the load, I don't know. > > It looks like there is a call to schedule_work. so this goes over keventd, right? > There are two pieces of the path. If you are switching in and out of a > tty controlled by something like X. User space has to grant > permission before the operation happens. Where there isn't a gate > keeper I know it is cheaper but I don't know by how much, I suspect > there is still a schedule happening in there. Could keventd perhaps be starved? Willy, to exclude this possibility, could you perhaps chrt keventd to RT priority? If events/0 is PID 5 then the command to set it to SCHED_FIFO:50 would be: chrt -f -p 50 5 but ... events/0 is reniced to -5 by default, so it should definitely not be starved. Ingo