From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CCEE434D912 for ; Fri, 27 Mar 2026 09:50:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774605016; cv=none; b=eVP3vmyCa/5DMHX9kxboz44hIQp/FRmXqDU+b3GCpWBt77D2jLX2WUt3yBYOv1G14dl5VdAn52wrmZ/G+D32ELvpm3SdISDFR4lBd26L59BFD/vzfvr3u9Ei58qr1VtiiG5qoKG1ypv1eO/mw78cAFNTJytF616zlwNIKSJh7qc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774605016; c=relaxed/simple; bh=xGqDhRLT0ONetRUEOxZc/0mC+NNriKwAeI+b3xAsydc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=OH+P9QBdftKLgQ/oNJfWCT3BIyfjBLQg9VzCDfyGzSAzLk8DJWrknqtwuisGvvJMD1EACXqr0LIEgqbzrMYxzIvOKqArIfCxy7wvwcuSSiu0NybOvST0lFW2QVagRGoHl7sF7eSGPRCiRy8iLQ5YwrVdX0quZ1UJo1zT2hRdmAk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=HSPKfmR1; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="HSPKfmR1" 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 2E3C235A1; Fri, 27 Mar 2026 02:50:08 -0700 (PDT) Received: from [10.1.196.46] (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C93E63F915; Fri, 27 Mar 2026 02:50:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1774605014; bh=xGqDhRLT0ONetRUEOxZc/0mC+NNriKwAeI+b3xAsydc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=HSPKfmR1Pfenjxu9tz32Aa30xPUnJs4sSBngvS4tlWPwJkUE3tdq/TgCaudiHSbjL qym9k6HpuKuXmjHB9B2Hz3I0lYodoXZ+2tK8oDlzDaNy0LRQlitOVqQaV3fspGl9sc b10ZoPCZH6UOsMVPXnC/8DrsePvIxQlHBn2fYv3E= Message-ID: <599617aa-aade-4fde-9efa-79d592f1ff3f@arm.com> Date: Fri, 27 Mar 2026 09:50:09 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Thunderbird Daily Subject: Re: [RFC PATCH v2 1/5] arm_mpam: resctrl: Pick classes for use as mbm counters To: "Shaopeng Tan (Fujitsu)" 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" , "xhao@linux.alibaba.com" , "zengheng4@huawei.com" References: <20260319165540.381410-1-ben.horgan@arm.com> <20260319165540.381410-2-ben.horgan@arm.com> Content-Language: en-US From: Ben Horgan In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Shaopeng, On 3/27/26 02:53, Shaopeng Tan (Fujitsu) wrote: > Hello Ben, > > >> resctrl has two types of counters, NUMA-local and global. MPAM can only >> count global either using MSC at the L3 cache or in the memory controllers. >> When global and local equate to the same thing continue just to call it >> global. >> >> Tested-by: Shaopeng Tan >> Tested-by: Zeng Heng >> Reviewed-by: Shaopeng Tan >> Reviewed-by: Jonathan Cameron >> Signed-off-by: James Morse >> Signed-off-by: Ben Horgan > > There are environments with multiple L3 caches within a single NUMA node. > In this case, mbm_total will be the sum of traffic from all caches within that NUAM node. > Is my understanding correct? No, currently you only get mbm_total if there is single L3 cache and a single corresponding NUMA node. Rather than adding partial support by summing across numa nodes we plan to add support for memory bandwidth monitoring with NUMA node scope. Thanks, Ben > > > Best regards, > Shaopeng TAN