Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030181AbWHMC6u (ORCPT ); Sat, 12 Aug 2006 22:58:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932672AbWHMC6u (ORCPT ); Sat, 12 Aug 2006 22:58:50 -0400 Received: from mail.ocs.com.au ([202.147.117.210]:30254 "EHLO mail.ocs.com.au") by vger.kernel.org with ESMTP id S932667AbWHMC6t (ORCPT ); Sat, 12 Aug 2006 22:58:49 -0400 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.1 From: Keith Owens To: linux-kernel@vger.kernel.org Cc: sam@ravnborg.org Subject: 2.6.18-rc1 make -j4 does not run parallel Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 13 Aug 2006 12:58:51 +1000 Message-ID: <3740.1155437931@ocs10w.ocs.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1414 Lines: 28 Dual cpu system. 'echo $$' reports current id is 4972 export KBUILD_OUTPUT=../obj make -j4 Building a 2.6.17.7 tree, 'LANG= pstree -pl 4972' shows multiple tasks running in parallel. Even here it is only running 2 instead of the 4 that I expect. bash(4972)---make(7519)---make(7522)-+-make(7721)---make(8198)---make(8513)---sh(8565)---gcc(8566)---gcc(8572)-+-as(8574) | `-cc1(8573) `-make(8077)---sh(8558)---gcc(8559)---gcc(8569)-+-as(8571) `-cc1(8570) build a 2.6.18-rc1 or later tree, make -j4 does not run parallel. All pstree output shows a single branch, like this. bash(4972)---make(30031)---make(30034)---make(31797)---make(2840)---sh(3678)---gcc(3681)---gcc(3682)---cc1(3683) Using 'make -j' without a number or 'make -j' where is greater than 4 does show parallel build behaviour. Looks like something is decrementing -j as you go down the make tree and decrementing it enough that it ends up in a serial build. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/