Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755150Ab2E2S64 (ORCPT ); Tue, 29 May 2012 14:58:56 -0400 Received: from am1ehsobe003.messaging.microsoft.com ([213.199.154.206]:30293 "EHLO am1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755029Ab2E2S6z (ORCPT ); Tue, 29 May 2012 14:58:55 -0400 X-Forefront-Antispam-Report: CIP:163.181.249.108;KIP:(null);UIP:(null);IPV:NLI;H:ausb3twp01.amd.com;RD:none;EFVD:NLI X-SpamScore: -12 X-BigFish: VPS-12(zz936eK1432N98dKzz1202hzzz2dh668h839h93fhd25hf0ah) X-WSS-ID: 0M4SSPY-01-3WP-02 X-M-MSG: Date: Tue, 29 May 2012 20:58:43 +0200 From: Andreas Herrmann To: Peter Zijlstra CC: Mike Galbraith , lkml , Suresh Siddha , Paul Turner , Arjan Van De Ven Subject: Re: [rfc][patch] select_idle_sibling() inducing bouncing on westmere Message-ID: <20120529185843.GA20289@alberich.amd.com> References: <1337857490.7300.19.camel@marge.simpson.net> <1337865431.9783.148.camel@laptop> <1337865641.9783.149.camel@laptop> <1337926468.5415.48.camel@marge.simpson.net> <1338014259.7302.26.camel@marge.simpson.net> <1338017364.14636.9.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: <1338017364.14636.9.camel@twins> User-Agent: Mutt/1.5.21 (2010-09-15) X-OriginatorOrg: amd.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1645 Lines: 53 On Sat, May 26, 2012 at 09:29:24AM +0200, Peter Zijlstra wrote: > On Sat, 2012-05-26 at 08:37 +0200, Mike Galbraith wrote: > > > Ew. 3.4 went broke for Q6600, and performance went... far far away. > > > > [ 0.200057] CPU0 attaching sched-domain: > > [ 0.204016] domain 0: span 0-3 level MC > > [ 0.208015] groups: 0 1 2 3 > > [ 0.210970] CPU1 attaching sched-domain: > > [ 0.212014] domain 0: span 0-3 level MC > > [ 0.216016] groups: 1 2 3 0 > > [ 0.220016] CPU2 attaching sched-domain: > > [ 0.224015] domain 0: span 0-3 level MC > > [ 0.228016] groups: 2 3 0 1 > > [ 0.232015] CPU3 attaching sched-domain: > > [ 0.236016] domain 0: span 0-3 level MC > > [ 0.240017] groups: 3 0 1 2 > > > Oh yikes, I guess I wrecked > arch/x86/kernel/smpboot.c:cpu_coregroup_mask() in > 8e7fbcbc22c12414bcc9dfdd683637f58fb32759. > > That should very much always return llc mask, I just got that AMD case > confused. It looks like it should look like: > > > const struct cpumask *cpu_coregroup_mask(int cpu) > { > return cpu_llc_mask(cpu); > } > > And the AMD_DCM check was just to undo powersavings damage on > Magny-Cours or somesuch. IIRC returning cpu_core_mask() could even cause a panic in the scheduler, because the hierarchy of scheduling groups/domains was broken. > Andreas? Returning cpu_llc_mask is the right thing to do on AMD. Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/