From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1BE86C43381 for ; Fri, 22 Feb 2019 16:10:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E9DA820823 for ; Fri, 22 Feb 2019 16:10:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727121AbfBVQK0 (ORCPT ); Fri, 22 Feb 2019 11:10:26 -0500 Received: from outbound-smtp16.blacknight.com ([46.22.139.233]:44364 "EHLO outbound-smtp16.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725942AbfBVQK0 (ORCPT ); Fri, 22 Feb 2019 11:10:26 -0500 Received: from mail.blacknight.com (pemlinmail03.blacknight.ie [81.17.254.16]) by outbound-smtp16.blacknight.com (Postfix) with ESMTPS id B8A051C1EBB for ; Fri, 22 Feb 2019 16:10:23 +0000 (GMT) Received: (qmail 8503 invoked from network); 22 Feb 2019 16:10:23 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[37.228.225.79]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 22 Feb 2019 16:10:23 -0000 Date: Fri, 22 Feb 2019 16:10:22 +0000 From: Mel Gorman To: Peter Zijlstra Cc: Ingo Molnar , Thomas Gleixner , Paul Turner , Tim Chen , Linux List Kernel Mailing , subhra.mazumdar@oracle.com, Linus Torvalds , Fr?d?ric Weisbecker , Kees Cook , kerrnel@google.com Subject: Re: [RFC][PATCH 00/16] sched: Core scheduling Message-ID: <20190222161022.GZ9565@techsingularity.net> References: <20190218165620.383905466@infradead.org> <20190222124544.GY9565@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20190222124544.GY9565@techsingularity.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 22, 2019 at 12:45:44PM +0000, Mel Gorman wrote: > On Mon, Feb 18, 2019 at 09:49:10AM -0800, Linus Torvalds wrote: > > On Mon, Feb 18, 2019 at 9:40 AM Peter Zijlstra wrote: > > > > > > However; whichever way around you turn this cookie; it is expensive and nasty. > > > > Do you (or anybody else) have numbers for real loads? > > > > Because performance is all that matters. If performance is bad, then > > it's pointless, since just turning off SMT is the answer. > > > > I tried to do a comparison between tip/master, ht disabled and this series > putting test workloads into a tagged cgroup but unfortunately it failed > > [ 156.978682] BUG: unable to handle kernel NULL pointer dereference at 0000000000000058 > [ 156.986597] #PF error: [normal kernel read fault] > [ 156.991343] PGD 0 P4D 0 When bodged around, one test survived (performance was crucified but the benchmark is very synthetic). pgbench (test 2) paniced with a hard lockup. Most of the console log was corrupted (unrelated to the patch) but the relevant part is [ 4587.419674] Call Trace: [ 4587.419674] _raw_spin_lock+0x1b/0x20 [ 4587.419675] sched_core_balance+0x155/0x520 [ 4587.419675] ? __switch_to_asm+0x34/0x70 [ 4587.419675] __balance_callback+0x49/0xa0 [ 4587.419676] __schedule+0xf15/0x12c0 [ 4587.419676] schedule_idle+0x1e/0x40 [ 4587.419677] do_idle+0x166/0x280 [ 4587.419677] cpu_startup_entry+0x19/0x20 [ 4587.419678] start_secondary+0x17a/0x1d0 [ 4587.419678] secondary_startup_64+0xa4/0xb0 [ 4587.419679] Kernel panic - not syncing: Hard LOCKUP -- Mel Gorman SUSE Labs