From nobody Fri Dec 19 03:44:58 2025 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (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 A3F883090C2 for ; Wed, 17 Dec 2025 17:21:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.9 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765992123; cv=none; b=Z75GZ3fqiaeb1E0SAv+tlSB95xpLq8xnUZ6VRhWNUo1oib5eBRjFn7gJ+xvI/8T0POce1Z04S58I7d258s8bdi711+Z/Mw3qfuUe9j+inpscHQ6uZhIR43g5hjavu5+N23HuQ4qRPYI9wP9HJP8duSQgA3LxJBWc4lU25HwEZkU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765992123; c=relaxed/simple; bh=Tzc8GzLmIvmHCrhBSfUhxrDQ5mcGlRIeU8CM4rX1Yjk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Mh62cx5wBgMqOFLPgeIO86kWtBcUbhet2ZxZx/gUd0weWn8cvzd2QUqtLQ2xxBbYQ2GQ+keMhEBrtRaoAbp2u46RsNLeUlgJGtzSs6zWbtQn05w1tTY5zO1upapfpK7CP+TXWKmAERKIxwgV+YOM9/jq2hI2fXoERT/vdpsuGAw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=fail smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=bYCRMn35; arc=none smtp.client-ip=198.175.65.9 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=fail 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="bYCRMn35" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1765992117; x=1797528117; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Tzc8GzLmIvmHCrhBSfUhxrDQ5mcGlRIeU8CM4rX1Yjk=; b=bYCRMn35qPJJ1jASmUFTf7EjW7qrx7YhjEfJW8NGg9kcxfF360G72UJv A5W2qrxyUNkBdLfkNGa12pTu8CdVr25hZcuWawKwCRiM6cWyJFHdFr+gQ f81CR5ZSzhrt/PqnQQ/uM57ybDvwKOPM6k7/+tto9pGTCxq57qd8cnFWw 0vSrWsMCoFJCm48vb3iBVYk5YvraDUY29bI2ZoVFOtBk6WkrcLyhdHFPK 6SViNWcNyWRutY4fUhpB/M5dJT3E+DKBueoddwu8ja6SxykAVlaIy+Tys J6o+QMCcpPLkLi4q9Hgn2phw2t1w5pqppa1nEuwBIe/tyr6L4gTwWnwaB A==; X-CSE-ConnectionGUID: sY89SwI3Q0W5904noUa6Kw== X-CSE-MsgGUID: +mSVjVBdSIWxIZZUODtbDw== X-IronPort-AV: E=McAfee;i="6800,10657,11645"; a="90594706" X-IronPort-AV: E=Sophos;i="6.21,156,1763452800"; d="scan'208";a="90594706" Received: from fmviesa002.fm.intel.com ([10.60.135.142]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2025 09:21:34 -0800 X-CSE-ConnectionGUID: sd0xQ4ymSDyuaT8oy/L4mw== X-CSE-MsgGUID: oXARrLvCRrGK0zOCoan5dA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,156,1763452800"; d="scan'208";a="221748198" Received: from pgcooper-mobl3.ger.corp.intel.com (HELO agluck-desk3.home.arpa) ([10.124.223.131]) by fmviesa002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2025 09:21:33 -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 v17 12/32] x86,fs/resctrl: Support binary fixed point event counters Date: Wed, 17 Dec 2025 09:20:59 -0800 Message-ID: <20251217172121.12030-13-tony.luck@intel.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20251217172121.12030-1-tony.luck@intel.com> References: <20251217172121.12030-1-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" resctrl assumes that all monitor events can be displayed as unsigned decimal integers. Hardware architecture counters may provide some telemetry events with great= er precision where the event is not a simple count, but is a measurement of some sort (e.g. Joules for energy consumed). Add a new argument to resctrl_enable_mon_event() for architecture code to inform the file system that the value for a counter is a fixed-point value with a specific number of binary places. Only allow architecture to use floating point format on events that the file system has marked with mon_evt::is_floating_point which reflects the contract with user space on how the event values are displayed. Display fixed point values with values rounded to ceil(binary_bits * log10(= 2)) decimal places. Special case for zero binary bits to print "{value}.0". Signed-off-by: Tony Luck Reviewed-by: Reinette Chatre --- include/linux/resctrl.h | 3 +- fs/resctrl/internal.h | 8 ++++ arch/x86/kernel/cpu/resctrl/core.c | 6 +-- fs/resctrl/ctrlmondata.c | 74 ++++++++++++++++++++++++++++++ fs/resctrl/monitor.c | 10 +++- 5 files changed, 95 insertions(+), 6 deletions(-) diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h index 22c5d07fe9ff..c43526cdf304 100644 --- a/include/linux/resctrl.h +++ b/include/linux/resctrl.h @@ -412,7 +412,8 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r); u32 resctrl_arch_system_num_rmid_idx(void); int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid); =20 -void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu); +void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu, + unsigned int binary_bits); =20 bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid); =20 diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h index fb0b6e40d022..14e5a9ed1fbd 100644 --- a/fs/resctrl/internal.h +++ b/fs/resctrl/internal.h @@ -62,6 +62,9 @@ static inline struct rdt_fs_context *rdt_fc2context(struc= t fs_context *fc) * Only valid if @evtid is an MBM event. * @configurable: true if the event is configurable * @any_cpu: true if the event can be read from any CPU + * @is_floating_point: event values are displayed in floating point format + * @binary_bits: number of fixed-point binary bits from architecture, + * only valid if @is_floating_point is true * @enabled: true if the event is enabled */ struct mon_evt { @@ -71,6 +74,8 @@ struct mon_evt { u32 evt_cfg; bool configurable; bool any_cpu; + bool is_floating_point; + unsigned int binary_bits; bool enabled; }; =20 @@ -79,6 +84,9 @@ extern struct mon_evt mon_event_all[QOS_NUM_EVENTS]; #define for_each_mon_event(mevt) for (mevt =3D &mon_event_all[QOS_FIRST_EV= ENT]; \ mevt < &mon_event_all[QOS_NUM_EVENTS]; mevt++) =20 +/* Limit for mon_evt::binary_bits */ +#define MAX_BINARY_BITS 27 + /** * struct mon_data - Monitoring details for each event file. * @list: Member of the global @mon_data_kn_priv_list list. diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resct= rl/core.c index bd4a98106153..9222eee7ce07 100644 --- a/arch/x86/kernel/cpu/resctrl/core.c +++ b/arch/x86/kernel/cpu/resctrl/core.c @@ -902,15 +902,15 @@ static __init bool get_rdt_mon_resources(void) bool ret =3D false; =20 if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) { - resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false); + resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID, false, 0); ret =3D true; } if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) { - resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false); + resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID, false, 0); ret =3D true; } if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL)) { - resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID, false); + resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID, false, 0); ret =3D true; } if (rdt_cpu_has(X86_FEATURE_ABMC)) diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c index 2c69fcd70eeb..f319fd1a6de3 100644 --- a/fs/resctrl/ctrlmondata.c +++ b/fs/resctrl/ctrlmondata.c @@ -17,6 +17,7 @@ =20 #include #include +#include #include #include #include @@ -601,6 +602,77 @@ void mon_event_read(struct rmid_read *rr, struct rdt_r= esource *r, resctrl_arch_mon_ctx_free(r, evt->evtid, rr->arch_mon_ctx); } =20 +/* + * Decimal place precision to use for each number of fixed-point + * binary bits computed from ceil(binary_bits * log10(2)) except + * binary_bits =3D=3D 0 which will print "value.0" + */ +static const unsigned int decplaces[MAX_BINARY_BITS + 1] =3D { + [0] =3D 1, + [1] =3D 1, + [2] =3D 1, + [3] =3D 1, + [4] =3D 2, + [5] =3D 2, + [6] =3D 2, + [7] =3D 3, + [8] =3D 3, + [9] =3D 3, + [10] =3D 4, + [11] =3D 4, + [12] =3D 4, + [13] =3D 4, + [14] =3D 5, + [15] =3D 5, + [16] =3D 5, + [17] =3D 6, + [18] =3D 6, + [19] =3D 6, + [20] =3D 7, + [21] =3D 7, + [22] =3D 7, + [23] =3D 7, + [24] =3D 8, + [25] =3D 8, + [26] =3D 8, + [27] =3D 9 +}; + +static void print_event_value(struct seq_file *m, unsigned int binary_bits= , u64 val) +{ + unsigned long long frac =3D 0; + + if (binary_bits) { + /* Mask off the integer part of the fixed-point value. */ + frac =3D val & GENMASK_ULL(binary_bits - 1, 0); + + /* + * Multiply by 10^{desired decimal places}. The integer part of + * the fixed point value is now almost what is needed. + */ + frac *=3D int_pow(10ull, decplaces[binary_bits]); + + /* + * Round to nearest by adding a value that would be a "1" in the + * binary_bits + 1 place. Integer part of fixed point value is + * now the needed value. + */ + frac +=3D 1ull << (binary_bits - 1); + + /* + * Extract the integer part of the value. This is the decimal + * representation of the original fixed-point fractional value. + */ + frac >>=3D binary_bits; + } + + /* + * "frac" is now in the range [0 .. 10^decplaces). I.e. string + * representation will fit into chosen number of decimal places. + */ + seq_printf(m, "%llu.%0*llu\n", val >> binary_bits, decplaces[binary_bits]= , frac); +} + int rdtgroup_mondata_show(struct seq_file *m, void *arg) { struct kernfs_open_file *of =3D m->private; @@ -678,6 +750,8 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg) seq_puts(m, "Unavailable\n"); else if (rr.err =3D=3D -ENOENT) seq_puts(m, "Unassigned\n"); + else if (evt->is_floating_point) + print_event_value(m, evt->binary_bits, rr.val); else seq_printf(m, "%llu\n", rr.val); =20 diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c index 8c76ac133bca..844cf6875f60 100644 --- a/fs/resctrl/monitor.c +++ b/fs/resctrl/monitor.c @@ -988,16 +988,22 @@ struct mon_evt mon_event_all[QOS_NUM_EVENTS] =3D { }, }; =20 -void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu) +void resctrl_enable_mon_event(enum resctrl_event_id eventid, bool any_cpu,= unsigned int binary_bits) { - if (WARN_ON_ONCE(eventid < QOS_FIRST_EVENT || eventid >=3D QOS_NUM_EVENTS= )) + if (WARN_ON_ONCE(eventid < QOS_FIRST_EVENT || eventid >=3D QOS_NUM_EVENTS= || + binary_bits > MAX_BINARY_BITS)) return; if (mon_event_all[eventid].enabled) { pr_warn("Duplicate enable for event %d\n", eventid); return; } + if (binary_bits && !mon_event_all[eventid].is_floating_point) { + pr_warn("Event %d may not be floating point\n", eventid); + return; + } =20 mon_event_all[eventid].any_cpu =3D any_cpu; + mon_event_all[eventid].binary_bits =3D binary_bits; mon_event_all[eventid].enabled =3D true; } =20 --=20 2.52.0