From nobody Fri Dec 19 22:02:41 2025 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 4F44AC4167B for ; Thu, 30 Nov 2023 00:35:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343995AbjK3Aev (ORCPT ); Wed, 29 Nov 2023 19:34:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343848AbjK3Aej (ORCPT ); Wed, 29 Nov 2023 19:34:39 -0500 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4937A10E3; Wed, 29 Nov 2023 16:34:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1701304474; x=1732840474; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=6s4aliN2TmDzt5CeaX+F72a2OR8tCz3kRRQsDMwH6Bo=; b=TsawVPidHAASCFy/97WO9se52Y9abW5/FgpDWTIU1X8JFZaGED38PdTP pcR2yY7ufi+JC5gjyJ2AILsN0NUjgTvkQWYm8hUR+JeZVX8SgLloV15bu yRgAq2h2xBDMaUWtfu4t6cCsqv7ca4zt8nItOKQYD1dYPWhDM/o5m0+PO 4qSy5YvLobvqH1AOqEVX4jEj4iZ4Gy5g2iIsGNWuhTqIIsf2kgSun8j7l Z1jl6G4tloI0mZ/Dd0dBu2UX3Yc+4wY4PGqzR+93RXjy0MaQhOddDbf3T tkeADCIKs4DNFnmPTrr/UiED7L6YwQvY+VZPYEUgmtu6QWAFrTUjQrY51 Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10909"; a="392990697" X-IronPort-AV: E=Sophos;i="6.04,237,1695711600"; d="scan'208";a="392990697" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Nov 2023 16:34:29 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10909"; a="762499593" X-IronPort-AV: E=Sophos;i="6.04,237,1695711600"; d="scan'208";a="762499593" Received: from agluck-desk3.sc.intel.com ([172.25.222.74]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Nov 2023 16:34:28 -0800 From: Tony Luck To: Fenghua Yu , Reinette Chatre , Peter Newman , Jonathan Corbet , Shuah Khan , x86@kernel.org Cc: Shaopeng Tan , James Morse , Jamie Iles , Babu Moger , Randy Dunlap , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, patches@lists.linux.dev, Tony Luck , Shaopeng Tan Subject: [PATCH v12 8/8] x86/resctrl: Update documentation with Sub-NUMA cluster changes Date: Wed, 29 Nov 2023 16:34:18 -0800 Message-ID: <20231130003418.89964-9-tony.luck@intel.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20231130003418.89964-1-tony.luck@intel.com> References: <20231109230915.73600-1-tony.luck@intel.com> <20231130003418.89964-1-tony.luck@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" With Sub-NUMA Cluster mode enabled the scope of monitoring resources is per-NODE instead of per-L3 cache. Suffixes of directories with "L3" in their name refer to Sub-NUMA nodes instead of L3 cache ids. Users should be aware that SNC mode also affects the amount of L3 cache available for allocation within each SNC node. Signed-off-by: Tony Luck Reviewed-by: Peter Newman Reviewed-by: Reinette Chatre Reviewed-by: Shaopeng Tan Tested-by: Shaopeng Tan --- Documentation/arch/x86/resctrl.rst | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/re= sctrl.rst index a6279df64a9d..49ff789db1d8 100644 --- a/Documentation/arch/x86/resctrl.rst +++ b/Documentation/arch/x86/resctrl.rst @@ -366,10 +366,10 @@ When control is enabled all CTRL_MON groups will also= contain: When monitoring is enabled all MON groups will also contain: =20 "mon_data": - This contains a set of files organized by L3 domain and by - RDT event. E.g. on a system with two L3 domains there will - be subdirectories "mon_L3_00" and "mon_L3_01". Each of these - directories have one file per event (e.g. "llc_occupancy", + This contains a set of files organized by L3 domain or by NUMA + node (depending on whether Sub-NUMA Cluster (SNC) mode is disabled + or enabled respectively) and by RDT event. Each of these + directories has one file per event (e.g. "llc_occupancy", "mbm_total_bytes", and "mbm_local_bytes"). In a MON group these files provide a read out of the current value of the event for all tasks in the group. In CTRL_MON groups these files provide @@ -478,6 +478,23 @@ if non-contiguous 1s value is supported. On a system w= ith a 20-bit mask each bit represents 5% of the capacity of the cache. You could partition the cache into four equal parts with masks: 0x1f, 0x3e0, 0x7c00, 0xf8000. =20 +Notes on Sub-NUMA Cluster mode +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D +When SNC mode is enabled Linux may load balance tasks between Sub-NUMA +nodes much more readily than between regular NUMA nodes since the CPUs +on Sub-NUMA nodes share the same L3 cache and the system may report +the NUMA distance between Sub-NUMA nodes with a lower value than used +for regular NUMA nodes. Users who do not bind tasks to the CPUs of a +specific Sub-NUMA node must read the "llc_occupancy", "mbm_total_bytes", +and "mbm_local_bytes" for all Sub-NUMA nodes where the tasks may execute +to get the full view of traffic for which the tasks were the source. + +The cache allocation feature still provides the same number of +bits in a mask to control allocation into the L3 cache, but each +of those ways has its capacity reduced because the cache is divided +between the SNC nodes. The values reported in the resctrl +"size" files are adjusted accordingly. + Memory bandwidth Allocation and monitoring =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 --=20 2.41.0