From nobody Sun Feb 8 15:08:36 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 21B0129A322; Sat, 10 Jan 2026 19:46:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768074382; cv=none; b=rinoWCg+adfI2GhjLt+6OYKVWNTKmWMDd3IBo002HrP6Rob7JvzGGCValN8iI2YgglWitCXEDJtAJ9ikZdg2HezZHL86x46N3bdCAlm/Oj7q4q81LXngR+WZwKyFNamlbDmH3tGnMylByqWvyR9dLG3mvD81S/rtULao4tuDhpc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768074382; c=relaxed/simple; bh=8h0n1j8eYAS/1kyaOmhDMXGhnqA8bA24sgtf3QLbwMA=; h=Date:From:To:Subject:Cc:MIME-Version:Message-ID:Content-Type; b=iKTbb4jQynK+FVuO3hLYzc9A/dUduLImprfWqwQYKsrKACp7eScm7AuW/iyCXMuBfw5EMNC8A3BTf8MTAhDIQmqL+vFhOKY0VsPZ4DfgUmNrI0nCWDg13difXRrA4P+jAup2s1lD/OQFCRZfFNYCMvQAQZhx/GfEatNXKSrZucY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=zi7IIIcK; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=Po9WlgcS; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="zi7IIIcK"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="Po9WlgcS" Date: Sat, 10 Jan 2026 19:46:09 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1768074370; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=0fHU1C+Q6fr0Oby0kwmEoIOsnE2x5Cx4KnY9axF2BUI=; b=zi7IIIcKnAOCF6QMghfsQvGYcd2afM6cLsL0ZBIV5IL7Ydx0Cobu7zw7bcilQCKhVsCg5U RA5X8Q5GKBCtvg9GvQyxNMVzbuG5kciZ/ATlNOOE3Ml4WdfZNofjt3CkSsm6RNzehzO+mo sI1YfpYn33c69CISxhiIRRm+YV30qWlXxaqMksSzJTfXnG9LoQwgx4u1Cts3s7Jb9ZXr/E etIZ7srIq2hpNYAfZ3NmplQ7+SGwkRsjEhwiO/sKvviTDNmS3jvVQU5XvHyYdvcGkqH2Di oXzfcbuYs98Lco+2HvvOrY+qhnt8ayYP6558DVFqR54tUp1r9hWslDRYDA4cIQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1768074370; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=0fHU1C+Q6fr0Oby0kwmEoIOsnE2x5Cx4KnY9axF2BUI=; b=Po9WlgcS1ddklocBSXIj0JNja/tCi8NeS9jOnAuLFRuTtgkU/hYC4zfEK6EtAG21X6mqNw qyBsi0aBcnuWsLAQ== From: "tip-bot2 for Tony Luck" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/cache] x86,fs/resctrl: Support binary fixed point event counters Cc: Tony Luck , "Borislav Petkov (AMD)" , Reinette Chatre , x86@kernel.org, linux-kernel@vger.kernel.org Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <176807436938.510.9957444787817190746.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/cache branch of tip: Commit-ID: e37c9a3dc9f9645532780d5ef34ea3b8fcf9ddef Gitweb: https://git.kernel.org/tip/e37c9a3dc9f9645532780d5ef34ea3b8f= cf9ddef Author: Tony Luck AuthorDate: Wed, 17 Dec 2025 09:20:59 -08:00 Committer: Borislav Petkov (AMD) CommitterDate: Mon, 05 Jan 2026 16:10:41 +01:00 x86,fs/resctrl: Support binary fixed point event counters 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 so= me 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 contra= ct 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 Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://lore.kernel.org/20251217172121.12030-1-tony.luck@intel.com --- arch/x86/kernel/cpu/resctrl/core.c | 6 +- fs/resctrl/ctrlmondata.c | 74 +++++++++++++++++++++++++++++- fs/resctrl/internal.h | 8 +++- fs/resctrl/monitor.c | 10 +++- include/linux/resctrl.h | 3 +- 5 files changed, 95 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resct= rl/core.c index bd4a981..9222eee 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 2c69fcd..f319fd1 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 @@ out_ctx_free: 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 @@ checkresult: 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/internal.h b/fs/resctrl/internal.h index fb0b6e4..14e5a9e 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/fs/resctrl/monitor.c b/fs/resctrl/monitor.c index 8c76ac1..844cf68 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 diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h index 22c5d07..c43526c 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