From owner-freebsd-stable@FreeBSD.ORG Mon Oct 16 22:33:38 2006 Return-Path: X-Original-To: freebsd-stable@FreeBSD.org Delivered-To: freebsd-stable@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E8BA716A4D1 for ; Mon, 16 Oct 2006 22:33:38 +0000 (UTC) (envelope-from gad@FreeBSD.org) Received: from smtp6.server.rpi.edu (smtp6.server.rpi.edu [128.113.2.226]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5182D43D55 for ; Mon, 16 Oct 2006 22:33:37 +0000 (GMT) (envelope-from gad@FreeBSD.org) Received: from [128.113.24.47] (gilead.netel.rpi.edu [128.113.24.47]) by smtp6.server.rpi.edu (8.13.1/8.13.1) with ESMTP id k9GMXYiA001572; Mon, 16 Oct 2006 18:33:35 -0400 Mime-Version: 1.0 Message-Id: In-Reply-To: <200610131347.41023.kstewart@owt.com> References: <20061013143130.GW491@dev.null.cz> <200610131347.41023.kstewart@owt.com> Date: Mon, 16 Oct 2006 18:33:33 -0400 To: Kent Stewart , freebsd-stable@FreeBSD.org From: Garance A Drosehn Content-Type: text/plain; charset="us-ascii" ; format="flowed" X-CanItPRO-Stream: default X-RPI-SA-Score: undef - spam-scanning disabled X-Scanned-By: CanIt (www . canit . ca) Cc: Subject: Re: FreeBSD and "make -j# buildworld" usability X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Oct 2006 22:33:39 -0000 At 1:47 PM -0700 10/13/06, Kent Stewart wrote: >On Friday 13 October 2006 07:31, Buki wrote: >> Hi, >> >> I searched the archives and web a little but found many different >> opinions on stability/usability of using make -j# with buildworld >> (and buildkernel). >> >> So I am asking if it is a good idea to use make -j on production >> boxes. >> > >I tested buildworlds with different values for -j. On single processors, >using a script that basically looked like > >time make -j? ... > >yielded fastest builds when I didn't specify a value for -j. On dual >cpu's a value around -j8 yielded the fastest build. You might want to repeat those performance tests. The results will change over time, as various system changes are made. I used to see results somewhat similar to yours, but the last time I checked I seemed to get the best results from a dual-cpu system when using -j3 . I believe that change in performance is due to some improvements made to the `make' command itself, which solved some delays that happened when -j was used. However, I do not remember the details. Performance comparisons like this will also depend on all the hardware on the system, and not just the dual-CPU. It can change depending on much memory the machine has, for instance, or how fast the disks are compared to the CPU's. -- Garance Alistair Drosehn = drosehn@rpi.edu Senior Systems Programmer or gad@FreeBSD.org Rensselaer Polytechnic Institute; Troy, NY; USA