From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753509AbbCQSeP (ORCPT ); Tue, 17 Mar 2015 14:34:15 -0400 Received: from mail-wg0-f54.google.com ([74.125.82.54]:35295 "EHLO mail-wg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752789AbbCQSeN (ORCPT ); Tue, 17 Mar 2015 14:34:13 -0400 Message-ID: <550873A0.5030009@gmail.com> Date: Tue, 17 Mar 2015 19:34:08 +0100 From: poma User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Borislav Petkov CC: Community support for Fedora users , stan , Linux Kernel list Subject: Re: How to increase maximum user cpu usage allowed on a multi core system? References: <20150309120339.68ea8374@vfemail.net> In-Reply-To: <20150309120339.68ea8374@vfemail.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09.03.2015 20:03, stan wrote: > I'm running Fedora 21 with a custom compiled kernel, > 3.19.0-1.20150211.fc21.x86_64. > > I have a multi core system with 6 cores. All are recognized by the > kernel. > > But, when I run a compile job with -j6, in order to allow all six cores > to be used, it limits the total amount of usage to 100% of a *single* > core. So, it might use all six cores, but the sum of the percentages > on those six cores is always around 100% of one core. This is from > htop output. > > On large compilations, like the kernel or firefox, even using 4 cores > could drastically reduce compile time. > > I've looked at /etc/security/limits.conf, but it doesn't seem to have a > setting for this. I've also looked at the /proc system to see if there > is a kernel variable, though that seems unlikely, with no luck. Online > searching found ways to limit the amount that a single job can get, but > not how to set this for a user. There must be a configuration variable > somewhere that is limiting the amount of total cpu a user can use. But > I can't find it. > > Can anyone help? > Borislav, can you help explain the man why this is happening with his Piledriver. http://www.cpu-world.com/CPUs/Bulldozer/AMD-FX-Series%20FX-6300.html poma