From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965032AbWDMXPM (ORCPT ); Thu, 13 Apr 2006 19:15:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965035AbWDMXOw (ORCPT ); Thu, 13 Apr 2006 19:14:52 -0400 Received: from ns1.suse.de ([195.135.220.2]:14024 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S965032AbWDMXOm (ORCPT ); Thu, 13 Apr 2006 19:14:42 -0400 Date: Thu, 13 Apr 2006 16:13:30 -0700 From: Greg KH To: tyler@agat.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] Kmod optimization Message-ID: <20060413231330.GA6760@suse.de> References: <20060413180345.GA10910@Starbuck> <20060413182401.GA26885@suse.de> <20060413183617.GB10910@Starbuck> <20060413185014.GA27130@suse.de> <20060413190412.GA30541@Starbuck> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060413190412.GA30541@Starbuck> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 13, 2006 at 09:04:12PM +0200, tyler@agat.net wrote: > On Thu, Apr 13, 2006 at 11:50:14AM -0700, Greg KH wrote: > > On Thu, Apr 13, 2006 at 08:36:17PM +0200, tyler@agat.net wrote: > > > On Thu, Apr 13, 2006 at 11:24:01AM -0700, Greg KH wrote: > > > > On Thu, Apr 13, 2006 at 08:03:45PM +0200, tyler@agat.net wrote: > > > > > Hi, > > > > > > > > > > the request_mod functions try to load automatically a module by running > > > > > a user mode process helper (modprobe). > > > > > > > > > > The user process is launched even if the module is already loaded. I > > > > > think it would be better to test if the module is already loaded. > > > > > > > > Does this cause a problem somehow? request_mod is called _very_ > > > > infrequently from a normal kernel these days, so I really don't think > > > > this is necessary. > > > > > > Yes I agree it _should_ be very infrequently called but it _will_ be very > > > infrequently called just if the user space configuration is done properly. > > > > What do you mean by this? Almost all 2.6 distros use udev today, which > > prevents this code from ever getting called. So odds are, you are > > optimising something that no one will ever use :) > Well perhaps I don't understand the mechanism :) But let's take an > example. > On all kernels (even recent), if the module smbfs is loaded, it's not > handled by udev and request_module could be called. > > Let"s take another example to see to illustrate why I think > it depends on the user configuration : > module A depends on module B > > if we have a script which do "insmod moduleA.ko ; insmod moduleB.ko", > there will be a call to request_module. No, that script will fail. Try it out :) The kernel will not call out to try to resolve the symbols, that's up to userspace to handle. Hint, try running 'modprobe moduleA.ko' instead, it will handle the dependancies correctly. I still don't see where this is really needed... thanks, greg k-h