From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6DAA5F4BB69 for ; Tue, 24 Feb 2026 18:00:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Zm7+48Wrdc+GWnRgoDIp3WQUM+RRlPpTsMIDA4VWCyU=; b=cWIP0BFb8yY11nuMRE1diohrLS qCCWEePbPCEYEoj/nA16LMd8/1b99lqg0L1N07AJebPI6Q8QMVHhvG0pdId1WE2N7H8xk/2UIWckq 8i23RRfmxutBiRCb878NU3qkYegYdH5NWwcK+IYY4M2dG3b5ja0YJG6118bI0Jb+84bjngeZO+w40 E4wx06aLLHNw7ovy0piRWFtIGtYv+B51hFrwSpbQwkLS6BC0+aAG6NRjo9orSAMpQLC+CNdUofLqE 4q8JfbXiDp5XAFh85xxR2FninWei4YAYk5vWZgRDPCptc3HV9DWDbYufOEdtyNd3M8WbSyOnfBAv5 eXKmniWg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vuwha-00000002ZEX-2bGz; Tue, 24 Feb 2026 18:00:06 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vuwhV-00000002Z7H-2l9T for linux-arm-kernel@lists.infradead.org; Tue, 24 Feb 2026 18:00:03 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8A5E6339; Tue, 24 Feb 2026 09:59:54 -0800 (PST) Received: from e134344.cambridge.arm.com (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 275143F59E; Tue, 24 Feb 2026 09:59:55 -0800 (PST) From: Ben Horgan To: ben.horgan@arm.com Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, carl@os.amperecomputing.com, dave.martin@arm.com, david@kernel.org, dfustini@baylibre.com, fenghuay@nvidia.com, gshan@redhat.com, james.morse@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, peternewman@google.com, punit.agrawal@oss.qualcomm.com, quic_jiles@quicinc.com, reinette.chatre@intel.com, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, tan.shaopeng@fujitsu.com, xhao@linux.alibaba.com, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, kvmarm@lists.linux.dev, zengheng4@huawei.com, linux-doc@vger.kernel.org, Shaopeng Tan Subject: [PATCH v5 27/41] arm_mpam: resctrl: Add support for csu counters Date: Tue, 24 Feb 2026 17:57:06 +0000 Message-ID: <20260224175720.2663924-28-ben.horgan@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260224175720.2663924-1-ben.horgan@arm.com> References: <20260224175720.2663924-1-ben.horgan@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260224_100001_864896_E317411F X-CRM114-Status: GOOD ( 22.04 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: James Morse resctrl exposes a counter via a file named llc_occupancy. This isn't really a counter as its value goes up and down, this is a snapshot of the cache storage usage monitor. Add some picking code which will only find an L3. The resctrl counter file is called llc_occupancy but we don't check it is the last one as it is already identified as L3. Tested-by: Shaopeng Tan Tested-by: Zeng Heng Reviewed-by: Shaopeng Tan Reviewed-by: Jonathan Cameron Signed-off-by: James Morse Co-developed-by: Dave Martin Signed-off-by: Dave Martin Signed-off-by: Ben Horgan --- Changes since rfc: Allow csu counters however many partid or pmg there are else if -> if reduce scope of local variables drop has_csu Changes since v2: return -> break so works for mbwu in later patch add for_each_mpam_resctrl_mon return error from mpam_resctrl_monitor_init(). It may fail when is abmc allocation introduced in a later patch. Squashed in patch from Dave Martin: https://lore.kernel.org/lkml/20250820131621.54983-1-Dave.Martin@arm.com/ Changes since v3: resctrl_enable_mon_event() signature update Restrict the events considered num-rmid update Use raw_smp_processor_id() Tighten heuristics: Make sure it is the L3 Please shout if this means the counters aren't exposed on any platforms Drop tags due to change in policy/rework Changes since v4: Move generic monitor boilerplate to separate patch --- drivers/resctrl/mpam_resctrl.c | 83 ++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c index c14e59e8586d..a570cdf06feb 100644 --- a/drivers/resctrl/mpam_resctrl.c +++ b/drivers/resctrl/mpam_resctrl.c @@ -289,6 +289,28 @@ static bool class_has_usable_mba(struct mpam_props *cprops) return mba_class_use_mbw_max(cprops); } +static bool cache_has_usable_csu(struct mpam_class *class) +{ + struct mpam_props *cprops; + + if (!class) + return false; + + cprops = &class->props; + + if (!mpam_has_feature(mpam_feat_msmon_csu, cprops)) + return false; + + /* + * CSU counters settle on the value, so we can get away with + * having only one. + */ + if (!cprops->num_csu_mon) + return false; + + return true; +} + /* * Calculate the worst-case percentage change from each implemented step * in the control. @@ -602,6 +624,64 @@ static void mpam_resctrl_pick_mba(void) } } +static void counter_update_class(enum resctrl_event_id evt_id, + struct mpam_class *class) +{ + struct mpam_class *existing_class = mpam_resctrl_counters[evt_id].class; + + if (existing_class) { + if (class->level == 3) { + pr_debug("Existing class is L3 - L3 wins\n"); + return; + } + + if (existing_class->level < class->level) { + pr_debug("Existing class is closer to L3, %u versus %u - closer is better\n", + existing_class->level, class->level); + return; + } + } + + mpam_resctrl_counters[evt_id].class = class; +} + +static void mpam_resctrl_pick_counters(void) +{ + struct mpam_class *class; + + lockdep_assert_cpus_held(); + + guard(srcu)(&mpam_srcu); + list_for_each_entry_srcu(class, &mpam_classes, classes_list, + srcu_read_lock_held(&mpam_srcu)) { + /* The name of the resource is L3... */ + if (class->type == MPAM_CLASS_CACHE && class->level != 3) { + pr_debug("class %u is a cache but not the L3", class->level); + continue; + } + + if (!cpumask_equal(&class->affinity, cpu_possible_mask)) { + pr_debug("class %u does not cover all CPUs", + class->level); + continue; + } + + if (cache_has_usable_csu(class)) { + pr_debug("class %u has usable CSU", + class->level); + + /* CSU counters only make sense on a cache. */ + switch (class->type) { + case MPAM_CLASS_CACHE: + counter_update_class(QOS_L3_OCCUP_EVENT_ID, class); + break; + default: + break; + } + } + } +} + static int mpam_resctrl_control_init(struct mpam_resctrl_res *res) { struct mpam_class *class = res->class; @@ -1157,6 +1237,9 @@ int mpam_resctrl_setup(void) } } + /* Find some classes to use for monitors */ + mpam_resctrl_pick_counters(); + for_each_mpam_resctrl_mon(mon, eventid) { if (!mon->class) continue; // dummy resource -- 2.43.0