From nobody Tue Dec 2 00:46:14 2025 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.11]) (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 BCE10328273 for ; Mon, 24 Nov 2025 18:55:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.11 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764010518; cv=none; b=PeepPP3FJbFiLjHZ8KZ7/f5tYJFbZrq7yOzsmiJzDvcKYQkTEZGbmCMK/gHp2YABaZDVmJpwiAOK5skzsFONaYwH0+HLWrXfcIFASd7GRzjvHLpEIyi50L+Wa+xFfCSiqZ0v0uHBPZ0GlvAW6CyY5wt+iCSR9kdF8afrZEICGfY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764010518; c=relaxed/simple; bh=cE+HGYLq3Yqm4nqyvtg00Zeqbcbxe1oYuxCiT0sDMGo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PaG9jZRpcSQhg4vRasmkBIwBbhHRayyyKaj5o7dMw5/N60udBX8n7Hv2nOtDd2SqqV04ti1RKqZkw2v6j2QdS1QQvQUTahMB407jIit0bsxOVyLhDoGEtEidAMTGUXP2xoe7qL9lNJKXvkC/lZHoLrLmx0G8kGCPa10iArz6jm8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=QAKFIarX; arc=none smtp.client-ip=192.198.163.11 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="QAKFIarX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1764010516; x=1795546516; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=cE+HGYLq3Yqm4nqyvtg00Zeqbcbxe1oYuxCiT0sDMGo=; b=QAKFIarX+Aw6ODgQkKeh2I1NrkI1AL3ie1jrKBmvrrJ0BZkCO9fL2ePS +ZCw5I82SYlvc5x0rIMRQJT/cG97S+aC9DfltQFZLVlG78I3RrjLxMuzp GQs5fOcm+nJDougCEkloNsOqfMqUg3wEO0txg8wjo3bH3txxYChz8zO4G iNMhHfIL65ruDcaU1t/zlQnazDO4AzruYSpXWtb6odiskx/2yREN5X/7c 1102a6P79hociQxwvucnBvfD0S6ZkcJTevnOoyoc1uO6k6q1J/2S80wx8 uL215k7C7nq9uKVcvZMj5jo6OsY5YIjT1N/QDPAOPUn6/UyO0YvMgycu+ w==; X-CSE-ConnectionGUID: thtSyfJ3QsizV/Hfty8IXg== X-CSE-MsgGUID: ueKCiX1ATe2xHnmQnLrXRQ== X-IronPort-AV: E=McAfee;i="6800,10657,11623"; a="76636977" X-IronPort-AV: E=Sophos;i="6.20,223,1758610800"; d="scan'208";a="76636977" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Nov 2025 10:54:33 -0800 X-CSE-ConnectionGUID: EMqgfZCIRJW5zNFBgo2pCg== X-CSE-MsgGUID: 0P5NpPN5RqyvFCv3b2InOA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.20,223,1758610800"; d="scan'208";a="192225052" Received: from rfrazer-mobl3.amr.corp.intel.com (HELO agluck-desk3.home.arpa) ([10.124.222.153]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Nov 2025 10:54:33 -0800 From: Tony Luck To: Fenghua Yu , Reinette Chatre , Maciej Wieczor-Retman , Peter Newman , James Morse , Babu Moger , Drew Fustini , Dave Martin , Chen Yu Cc: x86@kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Tony Luck Subject: [PATCH v14 32/32] x86,fs/resctrl: Update documentation for telemetry events Date: Mon, 24 Nov 2025 10:54:09 -0800 Message-ID: <20251124185412.24155-33-tony.luck@intel.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251124185412.24155-1-tony.luck@intel.com> References: <20251124185412.24155-1-tony.luck@intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Update resctrl filesystem documentation with the details about the resctrl files that support telemetry events. Signed-off-by: Tony Luck --- Documentation/filesystems/resctrl.rst | 102 +++++++++++++++++++++++--- 1 file changed, 90 insertions(+), 12 deletions(-) diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesyst= ems/resctrl.rst index 8c8ce678148a..138d2663b03d 100644 --- a/Documentation/filesystems/resctrl.rst +++ b/Documentation/filesystems/resctrl.rst @@ -252,13 +252,12 @@ with respect to allocation: bandwidth percentages are directly applied to the threads running on the core =20 -If RDT monitoring is available there will be an "L3_MON" directory +If L3 monitoring is available there will be an "L3_MON" directory with the following files: =20 "num_rmids": - The number of RMIDs available. This is the - upper bound for how many "CTRL_MON" + "MON" - groups can be created. + The number of RMIDs supported by hardware for + L3 monitoring events. =20 "mon_features": Lists the monitoring events if @@ -484,6 +483,25 @@ with the following files: bytes) at which a previously used LLC_occupancy counter can be considered for re-use. =20 +If telemetry monitoring is available there will be a "PERF_PKG_MON" direct= ory +with the following files: + +"num_rmids": + The number of RMIDs for telemetry monitoring events. By default, + resctrl will not enable telemetry events of a particular type + ("perf" or "energy") if the number of RMIDs that can be tracked + concurrently for that type is lower than the total number of + RMIDs supported by that type. The user can force-enable each + type of telemetry events with the "rdt=3D" boot command line + option, but this may reduce the number of monitoring groups that + can be created. + +"mon_features": + Lists the telemetry monitoring events that are enabled on this system. + +The upper bound for how many "CTRL_MON" + "MON" can be created +is the smaller of the L3_MON and PERF_PKG_MON "num_rmids" values. + Finally, in the top level of the "info" directory there is a file named "last_cmd_status". This is reset with every "command" issued via the file system (making new directories or writing to any of the @@ -589,15 +607,40 @@ 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", - "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 - the sum for all tasks in the CTRL_MON group and all tasks in + This contains directories for each monitor domain. + + If L3 monitoring is enabled, there will be a "mon_L3_XX" directory for + each instance of an L3 cache. Each directory contains files for the enabl= ed + L3 events (e.g. "llc_occupancy", "mbm_total_bytes", and "mbm_local_bytes"= ). + + If telemetry monitoring is enabled, there will be a "mon_PERF_PKG_YY" + directory for each physical processor package. Each directory contains + files for the enabled telemetry events (e.g. "core_energy". "activity", + "uops_retired", etc.) + + The info/`*`/mon_features files provide the full list of enabled + event/file names. + + "core energy" reports a floating point number for the energy (in Joules) + consumed by cores (registers, arithmetic units, TLB and L1/L2 caches) + during execution of instructions summed across all logical CPUs on a + package for the current monitoring group. + + "activity" also reports a floating point value (in Farads). This provides + an estimate of work done independent of the frequency that the CPUs used + for execution. + + Note that "core energy" and "activity" only measure energy/activity in the + "core" of the CPU (arithmetic units, TLB, L1 and L2 caches, etc.). They + do not include L3 cache, memory, I/O devices etc. + + All other events report decimal integer values. + + 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 the sum for all tasks in the CTRL_MON group and all tasks in MON groups. Please see example section for more details on usage. + On systems with Sub-NUMA Cluster (SNC) enabled there are extra directories for each node (located within the "mon_L3_XX" directory for the L3 cache they occupy). These are named "mon_sub_L3_YY" @@ -1590,6 +1633,41 @@ Example with C:: resctrl_release_lock(fd); } =20 +Debugfs +=3D=3D=3D=3D=3D=3D=3D +In addition to the use of debugfs for tracing of pseudo-locking performanc= e, +architecture code may create debugfs directories associated with monitoring +features for a specific resource. + +The full pathname for these is in the form: + + /sys/kernel/debug/resctrl/info/{resource_name}_MON/{arch}/ + +The presence, names, and format of these files may vary between architectu= res +even if the same resource is present. + +PERF_PKG_MON/x86_64 +------------------- +Three files are present per telemetry aggregator instance that show status. +The prefix of each file name describes the type ("energy" or "perf"), the +guid, which processor package it belongs to, and the instance number of the +aggregator. For example: "energy_0x26696143_pkg1_agg2". + +The suffix describes which data is reported in the file and is one of: + +data_loss_count: + This counts the number of times that this aggregator + failed to accumulate a counter value supplied by a CPU. + +data_loss_timestamp: + This is a "timestamp" from a free running 25MHz uncore + timer indicating when the most recent data loss occurred. + +last_update_timestamp: + Another 25MHz timestamp indicating when the + most recent counter update was successfully applied. + + Examples for RDT Monitoring along with allocation usage =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=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D Reading monitored data --=20 2.51.1