From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.17]) (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 E6FB750AC38 for ; Mon, 28 Sep 2026 22:15:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790633758; cv=none; b=IiECWCJz9aEhk3MtWpLrTkMblT9qh69D9i8ML4wQw9zHWc4j+Ogm4/g6AU7KsQBAUaj18x2XInSDoT20jlpj5tSLbwd+O67mwIvmzGXxA1rB1nmLfSoWQbgrkaPnTPgXXMS4kKmjEd47wYC/Lqa4ec1Rp1bo6qsMmnLAUDym/Nw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790633758; c=relaxed/simple; bh=HRaGWkms3o2AV/USNZBUgC1MVEPrSsotLJzEAs7VjQ0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jMIgRAWPbdY+yIsPJSv+p2yfeAVVPVd9ljxdLAs7cJbKmFsMXzzufPWFCDzCTUzJ5B3mSYG4msXaQ+2oorIr+aYqBgdckZf+dz1uGJ42EEDPF1bCTxKQ/TuuTUSIqR2RcCKNeCv16J/XB/tXA9s7lpjh75adO2ghHqVKNxSxcR8= 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=GeDWrzBz; arc=none smtp.client-ip=198.175.65.17 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="GeDWrzBz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790633757; x=1822169757; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=HRaGWkms3o2AV/USNZBUgC1MVEPrSsotLJzEAs7VjQ0=; b=GeDWrzBzcdeEfcVR22fvdSbGQXqpX8rAVTPGr4yogNmfOYoVymAc4ctg XSXMbxxsR6xdk92kzC9oJOb3vCUREso75oIFmFrGYhslC21BRK5ExhB1v yxs4xUk72qkzfJZGgD4qgP6lbfWmcUD7xTbGZvSyPszI2Clk0mLvD3yHN 9zWz2AqNF4hzMAm7kA+DUT/RPEPN1W4WGS7hTUxXXq2CywneeJR7tzcvR jGrH1qoOV4zVkMGEAgxpSN6yp0IviXyz24Rdr9Tr65ZLy77lpIY+g6mtH XgN4zlV4cJXNAMKdhmTekb4YF0r13aY0/k9xQ8DUv2eP+6SfzwWZkL2uO g==; X-CSE-ConnectionGUID: 5U47IJT/Tbmk8dS7OsZ63Q== X-CSE-MsgGUID: iMjy9ra3SvmbcGjxK/THtw== X-IronPort-AV: E=McAfee;i="6800,10657,11919"; a="90387382" X-IronPort-AV: E=Sophos;i="6.27,129,1787036400"; d="scan'208";a="90387382" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2026 15:15:21 -0700 X-CSE-ConnectionGUID: ey560ApjQ8SfoX68oi0eEw== X-CSE-MsgGUID: 8jxHqtqjTdOjzifYcBudgA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,129,1787036400"; d="scan'208";a="274685555" Received: from lstrano-mobl6.amr.corp.intel.com (HELO agluck-desk3.intel.com) ([10.124.222.143]) by fmviesa007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2026 15:15:20 -0700 From: Tony Luck To: Fenghua Yu , Reinette Chatre , Maciej Wieczor-Retman , Peter Newman , James Morse , Babu Moger , Drew Fustini , Dave Martin , Chen Yu , David E Box , x86@kernel.org Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, patches@lists.linux.dev, Tony Luck Subject: [PATCH v13 25/25] x86,fs/resctrl: Document telemetry mount timing caveat Date: Mon, 28 Sep 2026 15:15:09 -0700 Message-ID: <20260928221509.68002-26-tony.luck@intel.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260928221509.68002-1-tony.luck@intel.com> References: <20260928221509.68002-1-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 The PMT driver enumerates telemetry features asynchronously, so an automatic mount of resctrl from /etc/fstab early in boot may occur before those features are available, resulting in them not being enabled in the mounted instance. Add a footnote to the 'If telemetry monitoring is enabled' sentence explaining the race and providing a solution. Signed-off-by: Tony Luck --- v13: Drop the "Mounting resctrl with telemetry" section. Include the solution in the footnote. --- Documentation/filesystems/resctrl.rst | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst index b52795e03303..dcae1076f863 100644 --- a/Documentation/filesystems/resctrl.rst +++ b/Documentation/filesystems/resctrl.rst @@ -629,7 +629,7 @@ When monitoring is enabled all MON groups will also contain: each instance of an L3 cache. Each directory contains files for the enabled 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" + 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.) @@ -668,6 +668,11 @@ When monitoring is enabled all MON groups will also contain: returned if the MBM event does not have an assigned counter in the CTRL_MON group nor in any of its associated MON groups. +.. [#] Telemetry features are enumerated asynchronously by the PMT driver, so + an automatic mount of resctrl from ``/etc/fstab`` at boot may not enable + them. To avoid this race, defer the mount until after the ``pmt_telemetry`` + module has loaded. + "mon_hw_id": Available only with debug option. The identifier used by hardware for the monitor group. On x86 this is the RMID. -- 2.55.0