From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.115]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 28FD86ABD for ; Thu, 30 Nov 2023 00:34:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="DpX9Q1Dw" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1701304475; x=1732840475; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=6s4aliN2TmDzt5CeaX+F72a2OR8tCz3kRRQsDMwH6Bo=; b=DpX9Q1Dw3I8f196AghJ24tYdLDJAyrpxqAja4xxxboPZgmQboaIdFUyq CKfXcC/zHQ68f020kgrL64fYbBhkZrrpKBSAp8M6anjPv+ssvWZBAYI+O MFXHMGNxe8mhvLiEuznE3y7kjzBKnC8aG1CPm/DsXa8riMWtcZoKWOYPZ 4rlAjhl4TY8H7rJPBHd1tkizCk7gp1ii2gcVFfrQIU160RYvxKN7ZcIqt Y1JMjCZo4oPnYdqlxTNT/sSujewAee+jootHpQvjY5h0XEdlcxVu3ASuf 26P7gaxWijUotW2iCQn+FsTxH5tYmYWbQX16wB00Ix2/yCX/Gp02CFccy w==; X-IronPort-AV: E=McAfee;i="6600,9927,10909"; a="392990695" X-IronPort-AV: E=Sophos;i="6.04,237,1695711600"; d="scan'208";a="392990695" 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> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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/resctrl.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: "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 with 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. +Notes on Sub-NUMA Cluster mode +============================== +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 ========================================== -- 2.41.0