From owner-freebsd-questions@FreeBSD.ORG Mon May 15 10:13:09 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 89EBC16A496 for ; Mon, 15 May 2006 10:13:09 +0000 (UTC) (envelope-from work@ashleymoran.me.uk) Received: from mercureh.reacthosting.com (reacthosting.com [195.177.245.34]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1D6CF43D78 for ; Mon, 15 May 2006 10:13:04 +0000 (GMT) (envelope-from work@ashleymoran.me.uk) Received: from hosta.jigsawfinance.com ([213.106.224.113] helo=alfie.jigsawhq.com) by mercureh.reacthosting.com with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.60 (FreeBSD)) (envelope-from ) id 1Ffa4V-0001YN-1Z for freebsd-questions@freebsd.org; Mon, 15 May 2006 11:13:03 +0100 From: Ashley Moran Organization: Codeweavers Ltd To: freebsd-questions@freebsd.org Date: Mon, 15 May 2006 11:12:33 +0100 User-Agent: KMail/1.9.1 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200605151112.33416.work@ashleymoran.me.uk> X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - mercureh.reacthosting.com X-AntiAbuse: Original Domain - freebsd.org X-AntiAbuse: Originator/Caller UID/GID - [0 0] / [26 6] X-AntiAbuse: Sender Address Domain - ashleymoran.me.uk X-Source: X-Source-Args: X-Source-Dir: Subject: Please explain make -j to my little brain X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 15 May 2006 10:13:09 -0000 Hi I've read the following snippet out of the handbook hundreds of times and still don't understand it. I even asked one of the developers I work with and he was baffled too. > It is now possible to specify a -j option to make which will cause it to > spawn several simultaneous processes. This is most useful on multi-CPU > machines. However, since much of the compiling process is IO bound rather > than CPU bound it is also useful on single CPU machines. What I want to know is, if compiling is IO bound, and you increase the number of simultaneous processes compiling your world, where do the extra processes get data from if the IO bandwidth is all used. Have I misunderstood the term IO bound? Please help, I feel like a right tool. Just as a side line... does anybody know the best -j value to build world on a 4-core box? Ashley -- "If you do it the stupid way, you will have to do it again" - Gregory Chudnovsky