From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 4 May 2002 04:05:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 4 May 2002 04:05:26 -0400 Received: from samba.sourceforge.net ([198.186.203.85]:44504 "HELO lists.samba.org") by vger.kernel.org with SMTP id ; Sat, 4 May 2002 04:05:25 -0400 From: Paul Mackerras MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15571.38378.376365.3387@argo.ozlabs.ibm.com> Date: Sat, 4 May 2002 18:03:54 +1000 (EST) To: Keith Owens Cc: linux-kernel@vger.kernel.org Subject: Re: kbuild 2.5 is ready for inclusion in the 2.5 kernel In-Reply-To: <15571.33592.365558.215598@argo.ozlabs.ibm.com> X-Mailer: VM 6.75 under Emacs 20.7.2 Reply-To: paulus@samba.org Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I wrote: > I seriously doubt that last statement. Building the global makefile > takes about 20 seconds on the box I compile on. On a kernel tree > without object files I can read all the files in the kernel tree in > about 0.8 seconds, and I can calculate an md5sum of every file in 3.2 > seconds. I can do an md5sum of all the Makefile.in's in 0.1 seconds. > This is with pp_makefile* compiled with -O2 -DNDEBUG=1. I made a mistake, the time to build the global makefile is in fact around 12 seconds with -O2 -DNDEBUG=1. And I should point out that this is a machine with enough RAM to keep the whole kernel tree in memory (so disk bandwidth is not an issue). I still think that the time to build the global makefile is big enough and obvious enough that many people (including myself) will want to see it optimized, either by making the process itself more efficient or by caching the result and re-using it where possible. Paul.