From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261575AbVF2QXq (ORCPT ); Wed, 29 Jun 2005 12:23:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261564AbVF2QXp (ORCPT ); Wed, 29 Jun 2005 12:23:45 -0400 Received: from mail1.kontent.de ([81.88.34.36]:62627 "EHLO Mail1.KONTENT.De") by vger.kernel.org with ESMTP id S261575AbVF2QWL (ORCPT ); Wed, 29 Jun 2005 12:22:11 -0400 From: Oliver Neukum To: Greg KH , Mike Bell , Dmitry Torokhov , linux-kernel@vger.kernel.org Subject: Re: [ANNOUNCE] ndevfs - a "nano" devfs Date: Wed, 29 Jun 2005 18:22:29 +0200 User-Agent: KMail/1.8 References: <20050624081808.GA26174@kroah.com> <200506290841.29785.oliver@neukum.org> <20050629160659.GA23594@kroah.com> In-Reply-To: <20050629160659.GA23594@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200506291822.29351.oliver@neukum.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Am Mittwoch, 29. Juni 2005 18:06 schrieben Sie: > On Wed, Jun 29, 2005 at 08:41:29AM +0200, Oliver Neukum wrote: > > What devfs and udev can do, and a static dev cannot, is names independent > > of order of detection. > > devfs can not do that. Why not? > > As for ressources, it is an illusion to think that user space means > > less ressources. A demon means page tables and a kernel stack. That > > 12K unswappable memory in the best case. > > You don't have to run the udevd process if you are worried about an What about events arriving out of order? > extra process in your kernel tables. Although this is the first time I > have heard anyone voice the "oh no, not another userspace task running" > point :) Well, you should have. 16K is a more realistic figure. Tasks have their cost. In fact: root 1 0.0 0.0 684 248 ? S 16:58 0:01 init [5] root 2 0.0 0.0 0 0 ? SN 16:58 0:00 [ksoftirqd/0] root 3 0.0 0.0 0 0 ? S< 16:58 0:00 [events/0] root 4 0.0 0.0 0 0 ? S< 16:58 0:00 [khelper] root 5 0.0 0.0 0 0 ? S< 16:58 0:00 [kthread] root 3424 0.0 0.1 2032 632 tty3 Ss+ 16:59 0:00 /sbin/mingetty tty3 root 3425 0.0 0.1 2032 632 tty4 Ss+ 16:59 0:00 /sbin/mingetty tty4 root 3426 0.0 0.1 2032 632 tty5 Ss+ 16:59 0:00 /sbin/mingetty tty5 root 3427 0.0 0.1 2032 632 tty6 Ss+ 16:59 0:00 /sbin/mingetty tty6 Counting this I arrive at 51*16K = 816K. That's a whole lot of unswappable memory. Thinking user space cheap is an automatic reflex these days. It's sometimes misleading like all blind reflexes. It makes me feel a fool for caring about __init and __exit. Regards Oliver