From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753737AbXDNST2 (ORCPT ); Sat, 14 Apr 2007 14:19:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753792AbXDNST2 (ORCPT ); Sat, 14 Apr 2007 14:19:28 -0400 Received: from 1wt.eu ([62.212.114.60]:1894 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753737AbXDNST1 (ORCPT ); Sat, 14 Apr 2007 14:19:27 -0400 Date: Sat, 14 Apr 2007 20:18:54 +0200 From: Willy Tarreau To: Ingo Molnar Cc: "Eric W. Biederman" , 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: <20070414181854.GA5826@1wt.eu> References: <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> <20070414175433.GA17527@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070414175433.GA17527@elte.hu> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 14, 2007 at 07:54:33PM +0200, Ingo Molnar wrote: > > * 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. Well, since I merged the fair-fork patch, I cannot reproduce (in fact, bash forks 1000 processes, then progressively execs scheddos, but it takes some time). So I'm rebuilding right now. But I think that Linus has an interesting clue about GPM and notification before switching the terminal. I think it was enabled in console mode. I don't know how that translates to frozen xterms, but let's attack the problems one at a time. Willy