From owner-freebsd-stable@freebsd.org Mon Jan 23 09:53:27 2017 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id CB5EACBC2AE for ; Mon, 23 Jan 2017 09:53:27 +0000 (UTC) (envelope-from killing@multiplay.co.uk) Received: from mail-wm0-x229.google.com (mail-wm0-x229.google.com [IPv6:2a00:1450:400c:c09::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 67538ABF for ; Mon, 23 Jan 2017 09:53:27 +0000 (UTC) (envelope-from killing@multiplay.co.uk) Received: by mail-wm0-x229.google.com with SMTP id r126so124046813wmr.0 for ; Mon, 23 Jan 2017 01:53:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=multiplay-co-uk.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to; bh=eth/CCZ/Vpj3bATG4McR2RQZjKP0qtPeAA+Z7cZquTk=; b=q6y2Plg1VIIrHA75XHME5okYRWQ+qNqjzP9MXsC6ayyZ+Dpd12KbeqCQREe/2opXSG xIBMg83z09TJCJCebykUjdheZo/TKjD53t9p4OQnXal8BZGL08t6isNVco75zIL5W+k5 D5x2VmsONWT678RPKEEKNkjrT5J+mWIMbPWysQg+0hI9FvzhH4j9mJqt3BVtzShldN9X gSFvqsxkq4Ttyk4qT+RknIWSGasCjAtfRyLi++WCRQxfw4v34fUgvqiRfdW8vuaDq75N WjyrVZksNxSKpN4xIMFsoCcQNHm0+Q8Y+T2B/jlIirynlwxDShH3fr0o1CnRJYXqrmeC Eb/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to; bh=eth/CCZ/Vpj3bATG4McR2RQZjKP0qtPeAA+Z7cZquTk=; b=ZhycAJeRibisPGOLRpg5YfrPVZbsQS4BWXi+IGKLD9Nmal5/m4cCTy6xHE6X5NvzwU hhxCi/X17E1FpFiIuX26ROeV2o7jE2a2TD8UzJxc+mZe8b+8F/D9G8R1bnQOAvJWtZ+t nFU0xbBNPPzYqN0p3MdK5QcznsYoSU4jkeE/0fJBNi+c6NglWMeBqJ/DbgClm/PtUZUU I+YdgBXSZBIqgbvCSd2Kr+Z/qasVLYLXA3kQpdZkmyuJPVus+8R5Gs9kkzSA1xy6JUaW z6N+8bNoIFjvCtCffzwOVngY94n1dH6/nYs975u2P6bNkIUHDlrLU1utT45V/XGd1Nhk UUXA== X-Gm-Message-State: AIkVDXJMPnXG/cfX2yPLY6Yy1sWYe/cJtxYxgWyIa8A1ipWUKIP1uiNgI8X+NdIu0NfX1a9W X-Received: by 10.223.163.154 with SMTP id l26mr27274121wrb.35.1485165204872; Mon, 23 Jan 2017 01:53:24 -0800 (PST) Received: from [10.10.1.58] ([185.97.61.26]) by smtp.gmail.com with ESMTPSA id s17sm13750487wrc.6.2017.01.23.01.53.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 23 Jan 2017 01:53:24 -0800 (PST) Subject: Re: Building Kernel and World with -j To: freebsd-stable@freebsd.org References: <20170123022457.606a0d8e@riseup.net> From: Steven Hartland Message-ID: <0ac0789a-35db-bed6-b01d-2d817c2e5933@multiplay.co.uk> Date: Mon, 23 Jan 2017 09:53:24 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: <20170123022457.606a0d8e@riseup.net> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.23 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, 23 Jan 2017 09:53:27 -0000 On 23/01/2017 07:24, Sergei Akhmatdinov wrote: > On Sun, 22 Jan 2017 22:57:46 -0800 > Walter Parker wrote: >> For decades there has always been a warning not to do parallel builds of >> the kernel or the world (Linux kernel builds also suggest not to do this). >> >> Every once in a while, I see people post about 5 minutes. This only way I >> can see this happening is by doing a parallel build (-j 16 on a Xeon >> Monster box). >> >> Are parallel builds safe? If not, what are actual risk factors and can they >> be mitigated? > Not only do I use -j, I also use ccache. > > Another option is to use WITH_META_MODE=YES, that's where most of the 5-minute > reports come from, I imagine. I haven't used it myself. > > My kernel takes 10 minutes with world taking about two hours. I generally just > leave them building overnight. > > The risks of parallel builds are mostly in the past, concurrency was still just > coming out and there were chances that something would get compiled before it's > dependency, breaking your compile and wasting all of those hours. > > Cheers, We always use -j for both kernel and world for years. While there's been a few niggles if the clock is out and its a rebuild they have been few and far between. Current cut down kernel build time is 1m and world build time is 22m here for FreeBSD 11.0-RELEASE on a dual E5-2640. Regards Steve