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, 16 Mar 2002 20:45:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 16 Mar 2002 20:45:26 -0500 Received: from mail.ocs.com.au ([203.34.97.2]:13572 "HELO mail.ocs.com.au") by vger.kernel.org with SMTP id ; Sat, 16 Mar 2002 20:45:15 -0500 X-Mailer: exmh version 2.2 06/23/2000 with nmh-1.0.4 From: Keith Owens To: "Martin J. Bligh" Cc: Anton Blanchard , lse-tech@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [Lse-tech] 7.52 second kernel compile In-Reply-To: Your message of "Sat, 16 Mar 2002 09:37:00 -0800." <730219199.1016271418@[10.10.2.3]> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 17 Mar 2002 12:45:03 +1100 Message-ID: <25310.1016329503@ocs3.intra.ocs.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 16 Mar 2002 09:37:00 -0800, "Martin J. Bligh" wrote: >Are you still doing something like this? ># MAKE="make -j14" /usr/bin/time make -j14 bzImage > >I tried setting the MAKE variable as well as doing the -j, >but it actually made kernel compile time slower - what difference >does it make on your machine? Can somebody clarify what this >actually does, as opposed to the -j on the command line? It depends on which version of make you are using. make 3.78 onwards has a built in job scheduler which shares the value of -j across its children, yea unto the nth generation. Earlier versions of make did a simplistic 'run -j copies of make at the top level' and did not propagate -j to the lower levels. With the recursive makefiles and make < 3.78 you need MAKE="make -j" to get a decent speedup because of the lack of choices at the top level Makefile. With make >= 3.79 you do not need MAKE="make -j14", it can interfere with make's own scheduler. See also make -l LOAD.