From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265619AbUEZPZe (ORCPT ); Wed, 26 May 2004 11:25:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265626AbUEZPZd (ORCPT ); Wed, 26 May 2004 11:25:33 -0400 Received: from zeus.kernel.org ([204.152.189.113]:17589 "EHLO zeus.kernel.org") by vger.kernel.org with ESMTP id S265601AbUEZPZR convert rfc822-to-8bit (ORCPT ); Wed, 26 May 2004 11:25:17 -0400 From: Con Kolivas To: Lenar =?iso-8859-1?q?L=F5hmus?= Subject: Re: 2.6.x kernel sluggish behavior Date: Thu, 27 May 2004 00:46:16 +1000 User-Agent: KMail/1.6.1 Cc: Linux Kernel Mailinglist References: <40B49BD6.7050202@vision.ee> In-Reply-To: <40B49BD6.7050202@vision.ee> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Message-Id: <200405270046.16429.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 26 May 2004 11:29 pm, Lenar Lõhmus wrote: > Hi. Hello > Overall I really like the performance and smoothness of 2.6.x kernels, Good to hear. > but there has been always one problematic situation. > > It's debian here with X/KDE running. The problem manifests itself > when one launches acroread-plugin in Mozilla or Mozilla-based browser. A known case. > I think it's definetely a scheduler problem (although caused by > application bug). This was one of my test cases for applications designed in a certain way that makes them prone to priority inversion. I tried extremely hard to find a workaround within the kernel and failed to do so. It only manifests with the acroread plugin in a gecko browser on uniprocessor, and seems to be some interaction within some gdk library if I recall correctly. Look through the kernel archives for my description of an earlier version of blender that exhibited this same problem. I suspect it's actually the binary only acroread and not the gdk library at fault. My solution was to simply make all .pdf files launch acroread separately. Generic solutions for tackling priority inversion prone application designs from within the kernel are expensive, and the best solution is to fix the application. No doubt a differently designed scheduler would be less prone to this particular interaction, but priority inversion is a "feature" of any dynamic priority design scheduler to some degree and it is the particular application that may or may not hit the resonant frequency (as I like to think of it) of each scheduler. Con