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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3D58CE7AF3 for ; Fri, 29 Sep 2023 21:06:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233179AbjI2VGY (ORCPT ); Fri, 29 Sep 2023 17:06:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232748AbjI2VGX (ORCPT ); Fri, 29 Sep 2023 17:06:23 -0400 Received: from mgamail.intel.com (mgamail.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 085BC1AA; Fri, 29 Sep 2023 14:06:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696021582; x=1727557582; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=v9BueRZQjerm83oD7OFPRBkzsAT7x+Db9BsxRYzoMU0=; b=TW5GmCP1ddk76NM8ajsqbPqR+QYaX6Y7PxvMBKCo6pMqqG9lA6HWflVu 1IZeKyQUvkVgWOwnbLlA7Km1jukG058ZtOkXfvDThu08BFK6n0zsL1UGX NnBQW3mNmmdbSijG06p8fGpWbszZzs0x02Y2eCiiR6emaMQGUkxxJetpj qE8O78MbR22zmLgRrkBvyeiVeTMsWT7a0XeFjMk4Y8uLXDzAgzDaJlmqG REUkrKECoST+GSnUkdf2Lr4e+MhvMPIu47NCU4xPPfP8TUHSJpC/1vISs 88YxAA0dsOk6RPK1tqVZzjNaUXZGSljhX8GLlRfK4g45YrL/pnShj+NlY A==; X-IronPort-AV: E=McAfee;i="6600,9927,10848"; a="446539373" X-IronPort-AV: E=Sophos;i="6.03,188,1694761200"; d="scan'208";a="446539373" Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2023 14:06:21 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10848"; a="923694203" X-IronPort-AV: E=Sophos;i="6.03,188,1694761200"; d="scan'208";a="923694203" Received: from agluck-desk3.sc.intel.com (HELO agluck-desk3) ([172.25.222.74]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Sep 2023 14:06:21 -0700 Date: Fri, 29 Sep 2023 14:06:19 -0700 From: Tony Luck To: Peter Newman Cc: Fenghua Yu , Reinette Chatre , Jonathan Corbet , Shuah Khan , x86@kernel.org, Shaopeng Tan , James Morse , Jamie Iles , Babu Moger , Randy Dunlap , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, patches@lists.linux.dev Subject: Re: [PATCH v6 0/8] Add support for Sub-NUMA cluster (SNC) systems Message-ID: References: <20230829234426.64421-1-tony.luck@intel.com> <20230928191350.205703-1-tony.luck@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Fri, Sep 29, 2023 at 04:33:17PM +0200, Peter Newman wrote: > Hi Tony, > > On Thu, Sep 28, 2023 at 9:14 PM Tony Luck wrote: > > > > The Sub-NUMA cluster feature on some Intel processors partitions > > the CPUs that share an L3 cache into two or more sets. This plays > > havoc with the Resource Director Technology (RDT) monitoring features. > > Prior to this patch Intel has advised that SNC and RDT are incompatible. > > > > Some of these CPU support an MSR that can partition the RMID > > counters in the same way. This allows for monitoring features > > to be used (with the caveat that memory accesses between different > > SNC NUMA nodes may still not be counted accuratlely. > > Is an "SNC NUMA node" a "sub-NUMA node", or a NUMA node on which SNC > has been enabled? It would be architecturally possible to enable SNC mode on a subset of CPU sockets. But there isn't a BIOS setup option to do that. You either have SNC everywhere, or nowhere. I prefer "SNC NUMA node" == "sub-NUMA node". This version "NUMA node on which SNC has been enabled" makes it sound like there is a control on a NUMA node that can be switched. The control is on the CPU socket. That's often equivalent to a NUMA node, but Intel has had CPUs in the past where this isn't the case (e.g. Cascade Lake -AP and Cooper Lake). > > Thanks! > -Peter Thanks for the review of the series. I've applied changes to my local tree. Will post v7 of the series early next week if no other reviews come in. -Tony