From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id 656CD139083 for ; Wed, 22 Nov 2017 08:32:09 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id A0ADFE0E67; Wed, 22 Nov 2017 08:32:03 +0000 (UTC) Received: from gw1.antarean.org (gw1.antarean.org [194.145.200.214]) by pigeon.gentoo.org (Postfix) with ESMTP id 3257CE0DE9 for ; Wed, 22 Nov 2017 08:32:03 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by gw1.antarean.org (Postfix) with ESMTP id A0B6C20859 for ; Wed, 22 Nov 2017 08:58:28 +0100 (CET) X-Virus-Scanned: amavisd-new at antarean.org Received: from gw1.antarean.org ([127.0.0.1]) by localhost (gw1.antarean.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 7xxWzjheIaE4 for ; Wed, 22 Nov 2017 08:58:27 +0100 (CET) Received: from mailstore1.antarean.org (localhost [127.0.0.1]) by gw1.antarean.org (Postfix) with ESMTP id 5194220848 for ; Wed, 22 Nov 2017 08:58:27 +0100 (CET) Received: from eve.localnet (eve.adm.antarean.org [10.55.16.44]) by mailstore1.antarean.org (Postfix) with ESMTP id 22E3732 for ; Wed, 22 Nov 2017 09:32:00 +0100 (CET) From: "J. Roeleveld" To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] is multi-core really worth it? Date: Wed, 22 Nov 2017 09:32:00 +0100 Message-ID: <2631935.PigJGvPPt2@eve> Organization: Antarean In-Reply-To: <20171122074808.r7thimlcnapg5gek@grusum.endjinn.de> References: <6b5fbeca-453c-f103-5e4e-a8db83a6dabf@st.com> <20171122074808.r7thimlcnapg5gek@grusum.endjinn.de> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Archives-Salt: ce99d782-62ee-437c-893a-adec2fc20561 X-Archives-Hash: 635dd1c7418957a5435a555c07c56ca9 On Wednesday, November 22, 2017 8:48:08 AM CET David Haller wrote: > Hello, > > On Wed, 22 Nov 2017, Raffaele Belardi wrote: > >rebuilding system and world with gcc-7.2.0 on a 6-core AMD CPU I have > >the impression that most of the ebuilds limit parallel builds to 1, 2 > >or 3 threads. > > Most should build with "many" cores, but some might be limited, but ... > > >I'm aware it is only an impression, I did not spend the > >night monitoring the process, but nevertheless every time I checked > >the load was very low. > > I guess you're mostly observing stalls because the (single-thread) > overhead of emerge, configure (etc.), which can also be IO-bound... > The actual builds probably goes so fast on your box, you hardly > notice unless they're rather big(gish). > > Some numbers for comparison, and I generally build with just one > thread in the background on my 2 core "old" Athlon II X2 250: > dev-libs/boost took a good 45mins to build with one thread. Divide by > 6 for your cores, divide again by about 2-3 for your newer cores and > you're in the 3:45min range for such a "biggie" as boost. Most other > stuff won't even peg your meter. > > So, your emerge is mostly IO and "emerge"-threads bound. Solution: > adjust your build-threads[1], and then adjust your emerge jobs! See > '--jobs' in 'man emerge'. Can't find where to set a default in a > config-file for that ATM, but you could always alias/function/script > emerge to something else, e.g. put this in your ~/.bashrc: Instead of all these aliases, simply edit your make.conf ( /etc/portage/ make.conf ) And edit (or add) the following lines: MAKEOPTS="--jobs 24 --load-average 48" EMERGE_DEFAULT_OPTS="--jobs 24 --load-average 48" Adjust the values to match your system, the above works fine on my desktop. CPU: Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz And 32GB ram. -- Joost