From owner-freebsd-questions@FreeBSD.ORG Mon Jun 9 05:35:04 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 979081065679 for ; Mon, 9 Jun 2008 05:35:04 +0000 (UTC) (envelope-from josh.carroll@gmail.com) Received: from yw-out-2324.google.com (yw-out-2324.google.com [74.125.46.31]) by mx1.freebsd.org (Postfix) with ESMTP id 4E7488FC1B for ; Mon, 9 Jun 2008 05:35:04 +0000 (UTC) (envelope-from josh.carroll@gmail.com) Received: by yw-out-2324.google.com with SMTP id 9so990207ywe.13 for ; Sun, 08 Jun 2008 22:35:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:reply-to :to:subject:cc:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=i5qRNmOfFrwMubLwFh3phTo9cACVJHcOG91o2DTj/Hs=; b=WRAtkcyGHifEZr+crJ1JtG56Ylbn9PxToQf5XTKVhs1D+zjKR7F4GR96/xDAZVBxx0 nk33x2VuBoo2/SEar5FXFc1CMS8fn8KCy9oa9BVSyW6mSbHEUHBDQUzNcRv4WVNLmix1 DkIbZCUq8i31t/diGJgtvKH5Q1TzcCwYtsjGE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:reply-to:to:subject:cc:in-reply-to :mime-version:content-type:content-transfer-encoding :content-disposition:references; b=ReeNCOCL9LYAMd3oOmOpGhYaiLyuR0tv0/q7gZKluuFx8x9OX/zXJsTlnfhXaV5vcd jNAS1xeT9eN6kMGZ4irhnSUoFlsQ3YP3ZEH9b69NLfhJ7ESbsGRs7POfxbgGTqyl1JkI XgGns2wh0TBmmK4KwyZyyFw+j+jl4qPCrsAcE= Received: by 10.151.108.13 with SMTP id k13mr5638646ybm.84.1212989703611; Sun, 08 Jun 2008 22:35:03 -0700 (PDT) Received: by 10.150.140.14 with HTTP; Sun, 8 Jun 2008 22:35:03 -0700 (PDT) Message-ID: <8cb6106e0806082235h7b9b0926uee377330133a89d6@mail.gmail.com> Date: Mon, 9 Jun 2008 01:35:03 -0400 From: "Josh Carroll" To: "Chuck Robey" In-Reply-To: <484C8F15.6050208@telenix.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <484BE376.9050301@webrz.net> <484C5D6C.9020401@brianwhalen.net> <484C8F15.6050208@telenix.org> Cc: Brian , freebsd-questions@freebsd.org Subject: Re: Make buildworld X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: josh.carroll@gmail.com List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Jun 2008 05:35:04 -0000 > I did some testing, at least for me, I get the most improvements when the number > of cores or processors equals the -j number. You can make it higher, even > double it, withoout hurting things, but 95% of the improvements come from > matching the number of processes to the number of available CPUs (and that' by > my own testing, not theory). I've found that on my Q6600 (quad core) system, the optimal is 8 though the improvements after 5 were minimal. It depends if the jobs are I/O bound or not and the scheduler. Although even with ffmpeg, the optimal number of threads with this quad core system is 8. On my previous system with a dual-core chip with the same hardware, the "magic number" was 4 (again, 2x the number of cores). This was with the ULE scheduler, I'm not sure if the same holds true for the 4BSD scheduler or not. And as you said, it's important to use make without -j if the build fails before reporting bugs, since there are no guarantees that world will build properly with multiple jobs. Josh