Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752911AbdIFJPt convert rfc822-to-8bit (ORCPT ); Wed, 6 Sep 2017 05:15:49 -0400 Received: from mail.fireflyinternet.com ([109.228.58.192]:50646 "EHLO fireflyinternet.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752422AbdIFJPn (ORCPT ); Wed, 6 Sep 2017 05:15:43 -0400 X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT From: Chris Wilson User-Agent: alot/0.3.6 To: Andy Lutomirski , "Ingo Molnar" , "Peter Zijlstra" , "linux-kernel@vger.kernel.org" References: In-Reply-To: Message-ID: <150468933360.28581.16446660443497682079@mail.alporthouse.com> Subject: Re: Abysmal scheduler performance in Linus' tree? Date: Wed, 06 Sep 2017 10:15:33 +0100 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1038 Lines: 21 Quoting Andy Lutomirski (2017-09-06 06:13:39) > I'm running e7d0c41ecc2e372a81741a30894f556afec24315 from Linus' tree > today, and I'm seeing abysmal scheduler performance. Running make -j4 > ends up with all the tasks on CPU 3 most of the time (on my > 4-logical-thread laptop). taskset -c 0 whatever puts whatever on CPU > 0, but plain while true; do true; done puts the infinite loop on CPU 3 > right along with the make -j4 tasks. > > This is on Fedora 26, and I don't think I'm doing anything weird. > systemd has enabled the cpu controller, but it doesn't seem to have > configured anything or created any non-root cgroups. > > Just a heads up. I haven't tried to diagnose it at all. There is an issue on !llc machines arising from numa_wake_wide() where processes are not spread widely across the low-power cores: https://patchwork.kernel.org/patch/9875581/ The patch we are using to fix the regression is https://cgit.freedesktop.org/drm-intel/commit/?h=topic/core-for-CI&id=6c362d9657293d700a8299acbeb2f1e24378f488 -Chris