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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 79B58C433E6 for ; Wed, 10 Feb 2021 01:28:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2958C64E05 for ; Wed, 10 Feb 2021 01:28:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235130AbhBJB2N convert rfc822-to-8bit (ORCPT ); Tue, 9 Feb 2021 20:28:13 -0500 Received: from mga05.intel.com ([192.55.52.43]:21183 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234551AbhBIXPI (ORCPT ); Tue, 9 Feb 2021 18:15:08 -0500 IronPort-SDR: etAdOsePmAyAf1N/sD47UcewexiXnZFNtt8PULqbh9jWl44ZtHzPaIvgl9/ao5OFtvWxuhdUPi NnhnKj5Q4GEw== X-IronPort-AV: E=McAfee;i="6000,8403,9890"; a="266811879" X-IronPort-AV: E=Sophos;i="5.81,166,1610438400"; d="scan'208";a="266811879" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Feb 2021 15:09:33 -0800 IronPort-SDR: 5yzAWkKk+XFlauNT+vDCOmRG0EKcs2UFVztFh0aRO1avF+aMzYYmJwQFU9Ud1DeKpKo2QMaMr4 qBH3IG8fobPw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,166,1610438400"; d="scan'208";a="420211131" Received: from fmsmsx605.amr.corp.intel.com ([10.18.126.85]) by fmsmga002.fm.intel.com with ESMTP; 09 Feb 2021 15:09:32 -0800 Received: from fmsmsx610.amr.corp.intel.com (10.18.126.90) by fmsmsx605.amr.corp.intel.com (10.18.126.85) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Tue, 9 Feb 2021 15:09:28 -0800 Received: from fmsmsx612.amr.corp.intel.com (10.18.126.92) by fmsmsx610.amr.corp.intel.com (10.18.126.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Tue, 9 Feb 2021 15:09:28 -0800 Received: from fmsmsx612.amr.corp.intel.com ([10.18.126.92]) by fmsmsx612.amr.corp.intel.com ([10.18.126.92]) with mapi id 15.01.2106.002; Tue, 9 Feb 2021 15:09:28 -0800 From: "Luck, Tony" To: "Schofield, Alison" , Thomas Gleixner , Ingo Molnar , Borislav Petkov CC: "x86@kernel.org" , "linux-kernel@vger.kernel.org" , Dave Hansen , Tim Chen , "H. Peter Anvin" , Peter Zijlstra , David Rientjes , Igor Mammedov , Prarit Bhargava , "brice.goglin@gmail.com" Subject: RE: [PATCH] x86, sched: Allow NUMA nodes to share an LLC on Intel platforms Thread-Topic: [PATCH] x86, sched: Allow NUMA nodes to share an LLC on Intel platforms Thread-Index: AQHW/zSlzL/JNCz2s0ObNbwCfjAg9apQcJ2A Date: Tue, 9 Feb 2021 23:09:27 +0000 Message-ID: References: <20210209223943.9834-1-alison.schofield@intel.com> In-Reply-To: <20210209223943.9834-1-alison.schofield@intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: dlp-product: dlpe-windows dlp-reaction: no-action dlp-version: 11.5.1.3 x-originating-ip: [10.22.254.132] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > +#define X86_BUG_NUMA_SHARES_LLC X86_BUG(25) /* CPU may enumerate an LLC shared by multiple NUMA nodes */ During internal review I wondered why this is a "BUG" rather than a "FEATURE" bit. Apparently, the suggestion for "BUG" came from earlier community discussions. Historically it may have seemed reasonable to say that a cache cannot span NUMA domains. But with more and more things moving off the motherboard and into the socket, this doesn't seem too weird now. -Tony