From nobody Sun Feb 8 05:53:40 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 A1FD24F21E; Mon, 19 Feb 2024 18:37:34 +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=1708367856; cv=none; b=NBGv39O4ujy5SGfUZJ6h6pDWLGiJBm64Pnm+haDsTWwEOp0dv5fT+keNCNnCGndG/0V2KkHE7ZIaKhEhYM9DHNwSFBCvyRhpWzUCnWbWhpmVV6L3AqWe/kdb/ebmH3vQKeclT+pVdiXmhfWzPS4KXxCOeUMFqdQH09a6/I+0fRQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708367856; c=relaxed/simple; bh=3LhB2Cc32ycfwFgJCLASszVAtPO+bLG3GmucGwUAgKU=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=Tb9xL7wnrNe0N/5EtAucN2nXQt0htpeQ2Q/C1Oqwp8kHtAzM7UfGsNlHpsBd5JpdZgNnkSb6NmHpq/Yp1fktzReXCRcPRGgODXGq8LTCta8He/Ve0Lu4nAEY2fsfA3KnumejbsTZpxfyNVwf+frznAdZhPogqdOfXaCs1VBlZnA= 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=R00vFsGc; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=AgeeArYr; 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="R00vFsGc"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="AgeeArYr" Date: Mon, 19 Feb 2024 18:37:32 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1708367852; 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: in-reply-to:in-reply-to:references:references; bh=P/FSIoO734aKd8R09mkaakq4E7h8DwgoN3XWQpDso8M=; b=R00vFsGc1mZXPdtWkn0wSmZWZMnRAHqeyCjdjL7HmzEEFkiL0l1WN+awInIBRs+/525Yzm /evXt1H+0xn7bwmkfLEkx3GSE1M0FXNr6TLLpQPP7aEhIYi47Xzw6ZERJapxLZgheP2fJn fb1DX16WL1hJrffNLmhZqeMS1hicWPonnIUa7rquW8VQplUBwOhhCTbEDRvZFQsihalNhu ZsNnFNHmFVJ2uzQQndWXld5wUhFL88fKi7wq/CkBPyKOH6hFOhTuYADy8EZu/6LxYzO0Z3 uQ84Z+k2NWdUYfHGA1qqtGhu5LYC1stJ36TWJ5FgpRRiVRvQX5FOWE41XsdGNA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1708367852; 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: in-reply-to:in-reply-to:references:references; bh=P/FSIoO734aKd8R09mkaakq4E7h8DwgoN3XWQpDso8M=; b=AgeeArYrgld8ocLCHs0VZRMqJtcAUmEY1aAM++EQc/23h1TP1FcR/UkOLvGOuQWR2s82tq LyHN1OiaqaWjHlBQ== From: "tip-bot2 for James Morse" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/cache] x86/resctrl: Add cpumask_any_housekeeping() for limbo/overflow Cc: James Morse , "Borislav Petkov (AMD)" , Shaopeng Tan , Reinette Chatre , Babu Moger , Peter Newman , Carl Worth , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20240213184438.16675-13-james.morse@arm.com> References: <20240213184438.16675-13-james.morse@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <170836785205.398.2136801348690724618.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: a4846aaf39455fe69fce3522b385319383666eef Gitweb: https://git.kernel.org/tip/a4846aaf39455fe69fce3522b38531938= 3666eef Author: James Morse AuthorDate: Tue, 13 Feb 2024 18:44:26=20 Committer: Borislav Petkov (AMD) CommitterDate: Fri, 16 Feb 2024 19:18:32 +01:00 x86/resctrl: Add cpumask_any_housekeeping() for limbo/overflow The limbo and overflow code picks a CPU to use from the domain's list of on= line CPUs. Work is then scheduled on these CPUs to maintain the limbo list and a= ny counters that may overflow. cpumask_any() may pick a CPU that is marked nohz_full, which will either penalise the work that CPU was dedicated to, or delay the processing of lim= bo list or counters that may overflow. Perhaps indefinitely. Delaying the over= flow handling will skew the bandwidth values calculated by mba_sc, which expects= to be called once a second. Add cpumask_any_housekeeping() as a replacement for cpumask_any() that pref= ers housekeeping CPUs. This helper will still return a nohz_full CPU if that is= the only option. The CPU to use is re-evaluated each time the limbo/overflow wo= rk runs. This ensures the work will move off a nohz_full CPU once a housekeepi= ng CPU is available. Signed-off-by: James Morse Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Shaopeng Tan Reviewed-by: Reinette Chatre Reviewed-by: Babu Moger Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Babu Moger Tested-by: Carl Worth # arm64 Link: https://lore.kernel.org/r/20240213184438.16675-13-james.morse@arm.com Signed-off-by: Borislav Petkov (AMD) --- arch/x86/kernel/cpu/resctrl/internal.h | 24 ++++++++++++++++++++++++ arch/x86/kernel/cpu/resctrl/monitor.c | 20 +++++++++++++------- 2 files changed, 37 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/r= esctrl/internal.h index b7b9d92..81f5de9 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -7,6 +7,7 @@ #include #include #include +#include =20 #include =20 @@ -55,6 +56,29 @@ /* Max event bits supported */ #define MAX_EVT_CONFIG_BITS GENMASK(6, 0) =20 +/** + * cpumask_any_housekeeping() - Choose any CPU in @mask, preferring those = that + * aren't marked nohz_full + * @mask: The mask to pick a CPU from. + * + * Returns a CPU in @mask. If there are housekeeping CPUs that don't use + * nohz_full, these are preferred. + */ +static inline unsigned int cpumask_any_housekeeping(const struct cpumask *= mask) +{ + unsigned int cpu, hk_cpu; + + cpu =3D cpumask_any(mask); + if (!tick_nohz_full_cpu(cpu)) + return cpu; + + hk_cpu =3D cpumask_nth_andnot(0, mask, tick_nohz_full_mask); + if (hk_cpu < nr_cpu_ids) + cpu =3D hk_cpu; + + return cpu; +} + struct rdt_fs_context { struct kernfs_fs_context kfc; bool enable_cdpl2; diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/re= sctrl/monitor.c index 101f1b1..38f85e5 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -761,7 +761,6 @@ static void mbm_update(struct rdt_resource *r, struct r= dt_domain *d, void cqm_handle_limbo(struct work_struct *work) { unsigned long delay =3D msecs_to_jiffies(CQM_LIMBOCHECK_INTERVAL); - int cpu =3D smp_processor_id(); struct rdt_domain *d; =20 mutex_lock(&rdtgroup_mutex); @@ -770,8 +769,11 @@ void cqm_handle_limbo(struct work_struct *work) =20 __check_limbo(d, false); =20 - if (has_busy_rmid(d)) - schedule_delayed_work_on(cpu, &d->cqm_limbo, delay); + if (has_busy_rmid(d)) { + d->cqm_work_cpu =3D cpumask_any_housekeeping(&d->cpu_mask); + schedule_delayed_work_on(d->cqm_work_cpu, &d->cqm_limbo, + delay); + } =20 mutex_unlock(&rdtgroup_mutex); } @@ -781,7 +783,7 @@ void cqm_setup_limbo_handler(struct rdt_domain *dom, un= signed long delay_ms) unsigned long delay =3D msecs_to_jiffies(delay_ms); int cpu; =20 - cpu =3D cpumask_any(&dom->cpu_mask); + cpu =3D cpumask_any_housekeeping(&dom->cpu_mask); dom->cqm_work_cpu =3D cpu; =20 schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay); @@ -791,7 +793,6 @@ void mbm_handle_overflow(struct work_struct *work) { unsigned long delay =3D msecs_to_jiffies(MBM_OVERFLOW_INTERVAL); struct rdtgroup *prgrp, *crgrp; - int cpu =3D smp_processor_id(); struct list_head *head; struct rdt_resource *r; struct rdt_domain *d; @@ -815,7 +816,12 @@ void mbm_handle_overflow(struct work_struct *work) update_mba_bw(prgrp, d); } =20 - schedule_delayed_work_on(cpu, &d->mbm_over, delay); + /* + * Re-check for housekeeping CPUs. This allows the overflow handler to + * move off a nohz_full CPU quickly. + */ + d->mbm_work_cpu =3D cpumask_any_housekeeping(&d->cpu_mask); + schedule_delayed_work_on(d->mbm_work_cpu, &d->mbm_over, delay); =20 out_unlock: mutex_unlock(&rdtgroup_mutex); @@ -828,7 +834,7 @@ void mbm_setup_overflow_handler(struct rdt_domain *dom,= unsigned long delay_ms) =20 if (!static_branch_likely(&rdt_mon_enable_key)) return; - cpu =3D cpumask_any(&dom->cpu_mask); + cpu =3D cpumask_any_housekeeping(&dom->cpu_mask); dom->mbm_work_cpu =3D cpu; schedule_delayed_work_on(cpu, &dom->mbm_over, delay); }