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 9A311139082 for ; Fri, 1 Dec 2017 10:40:06 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 77C57E0BEB; Fri, 1 Dec 2017 10:39:56 +0000 (UTC) Received: from gw1.antarean.org (gw1.antarean.org [194.145.200.214]) by pigeon.gentoo.org (Postfix) with ESMTP id 05565E0BDF for ; Fri, 1 Dec 2017 10:39:54 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by gw1.antarean.org (Postfix) with ESMTP id D4F0A21462 for ; Fri, 1 Dec 2017 11:00:56 +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 3Z16QQ667wE7 for ; Fri, 1 Dec 2017 11:00:55 +0100 (CET) Received: from mailstore1.antarean.org (localhost [127.0.0.1]) by gw1.antarean.org (Postfix) with ESMTP id 9F1042084A for ; Fri, 1 Dec 2017 11:00:55 +0100 (CET) Received: from lan001.nl.antarean.org (lan001.nl.antarean.org [10.20.13.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mailstore1.antarean.org (Postfix) with ESMTPSA id 81EEA32 for ; Fri, 1 Dec 2017 11:39:51 +0100 (CET) Date: Fri, 01 Dec 2017 10:39:49 +0000 In-Reply-To: <1fc0daf3-b9f8-8e55-9194-93995d0244f1@st.com> References: <6b5fbeca-453c-f103-5e4e-a8db83a6dabf@st.com> <1fc0daf3-b9f8-8e55-9194-93995d0244f1@st.com> 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-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [gentoo-user] Re: is multi-core really worth it? To: gentoo-user@lists.gentoo.org From: "J. Roeleveld" Message-ID: <085728BB-DEC0-4891-B5EE-A601167839C4@antarean.org> X-Archives-Salt: 6b153aee-06f2-4fd1-a386-5253eaaed850 X-Archives-Hash: 35298c6594d8d436e136bdecc2e7f93e On 28 November 2017 11:07:58 GMT+01:00, Raffaele Belardi wrote: >Raffaele Belardi wrote: >> Hi, >>=20 >> rebuilding system and world with gcc-7=2E2=2E0 on a 6-core AMD CPU I ha= ve >the impression that >> most of the ebuilds limit parallel builds to 1, 2 or 3 threads=2E 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=2E >>=20 >> Does anyone have real-world statistics of CPU usage based on gentoo >world build? > >I graphed the number of parallel ebuilds while doing an 'emerge -e' >world on a 4-core CPU, >the graph is attached=2E There is an initial peak of ebuilds but I assume >it is fake data >due to prints being delayed=2E Then there is a long interval during which >there are few (~2) >ebuilds running=2E This may be due to lack of data (~700Mb still had to >be downloaded when I >started the emerge) or due to dependencies=2E Then, after ~500 merged >packages, finally the >number of parallel ebuilds rises to something very close to the >requested 5=2E > >Note: the graph represents the number of parallel ebuilds in time, not >the number of >parallel jobs=2E The latter would be more interesting but requires a lot >more effort=2E > >Note also in the log near the seamonkey build that the load rises to 15 >jobs; I suppose >seamonkey and other two potentially massively parallel jobs started >with low parallelism, >fooling emerge into starting all three of them, but then each one >spawned the full -j5 >jobs requested by MAKEOPTS=2E There's little emerge can do in these cases >to maintain the >load-average=2E > >All of this just to convince myself that yes, it is worth it! > >raffaele > >Method: >The relevant part of the command line: ># "MAKEOPTS=3D-j5 EMERGE_DEFAULT_OPTS=3D--jobs 3 --load-average 5" emerge >-e world >on a 4 core CPU=2E >In the log I substituted a +1 for every 'Emerging' and -1 for every >'Installing', removed >the rest of the line, summed and graphed the result=2E Add the load average part to the makeopts and make will keep the jobs down= when load rises=2E -- Joost --=20 Sent from my Android device with K-9 Mail=2E Please excuse my brevity=2E