From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751646AbdFHUAz (ORCPT ); Thu, 8 Jun 2017 16:00:55 -0400 Received: from merlin.infradead.org ([205.233.59.134]:51550 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751405AbdFHUAy (ORCPT ); Thu, 8 Jun 2017 16:00:54 -0400 Date: Thu, 8 Jun 2017 22:00:41 +0200 From: Peter Zijlstra To: Dave Hansen Cc: linux-kernel@vger.kernel.org, tony.luck@intel.com, tim.c.chen@linux.intel.com, bp@alien8.de, rientjes@google.com, imammedo@redhat.com, torvalds@linux-foundation.org, prarit@redhat.com, toshi.kani@hp.com, brice.goglin@gmail.com, hpa@linux.intel.com, mingo@kernel.org Subject: Re: [PATCH] x86, sched: allow topolgies where NUMA nodes share an LLC Message-ID: <20170608200041.GB8337@worktop.programming.kicks-ass.net> References: <20170608193928.A3B5497F@viggo.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170608193928.A3B5497F@viggo.jf.intel.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 08, 2017 at 12:39:28PM -0700, Dave Hansen wrote: > > From: Dave Hansen > > Our SMP boot code has a series of assumptions about what NUMA > nodes are that are enforced via topology_sane(). Once upon a > time, we verified that a CPU package only contained a single node > (fixed in cebf15eb0). Today, we verify that SMT siblings and > LLCs do not span nodes. > > The SMT siblings assumption is safe, but the LLC is violated on > current hardware. What does? That does sound broken. How can a cache domain sanely span memory controllers? This needs far more explanation.