From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934417AbcLTOAc (ORCPT ); Tue, 20 Dec 2016 09:00:32 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:34852 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933850AbcLTN73 (ORCPT ); Tue, 20 Dec 2016 08:59:29 -0500 Date: Tue, 20 Dec 2016 14:59:29 +0100 From: Peter Zijlstra To: Alexandre-Xavier =?iso-8859-1?Q?Labont=E9-Lamoureux?= Cc: linux-kernel@vger.kernel.org Subject: Re: Scheduler patches: 6x performance increase when system is under heavy load Message-ID: <20161220135929.GP3124@twins.programming.kicks-ass.net> References: <20161213134054.GU3207@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry for the delay, got side-tracked for a bit.. On Wed, Dec 14, 2016 at 12:15:25AM -0500, Alexandre-Xavier Labonté-Lamoureux wrote: > > Which of the 4 patches does this? > > I used all the 4 patches at the same time. Each patch fixes a > different bug. Would you like me to try each of them individually? Yes. > Were you already aware of each of these bugs? I had seen the paper and the patches. One of the issues has been fixed, one is a non-issue and we had ideas about at least one other and I cannot quite remember what the 4th was. > > Also, what hypervisor are you using and what does the output of booting > > with "sched_debug" look like? > > I was running the distro in VirualBox on Fedora. Here's the info from > /proc/sched_debug: > https://justpaste.it/11dhb > dmesg: https://justpaste.it/11dhr > Ah, I meant dmesg with the "sched_debug" boot cmdline option (and probably: "debug ignore_loglevel" added too) of the unmodified kernel. > > Lastly, can you reproduce on real hardware? > > No. On real hardware, I tested in Ubuntu on an i7-4790 3.60GHz CPU > without disabling HT and I saw no difference between CFS, the patched > kernel and MuQSS. If I get to know a reason why one would be better > than the other, I'd take the time to test it on more hardware. I'm > curious how I got such a performance improvement in my VM. OK, I'll also have to look at VirtualBox sources to see if they use paravirt locking bits, not having support for that could make a significant difference I suppose.