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([39.170.101.209]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b17db7fc2dsm4448216a91.13.2026.11.11.05.05.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Nov 2026 05:05:07 -0800 (PST) From: Ping Li To: yin.li@oss.qualcomm.com Cc: sdonthineni@nvidia.com, james.morse@arm.com, robh@kernel.org, ben.horgan@arm.com, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Ping Li Subject: Re: [PATCH v5 6/7] arm_mpam: Add support for memory controller MSC on DT platforms Date: Wed, 11 Nov 2026 21:04:57 +0800 Message-Id: <20261111130457.4143667-1-leeonion.muyu@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: <20261109-mpam-resctrl-dt-knp-support-v5-6-150335a79381@oss.qualcomm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Yin, Happy to share more details. 1. Our SoC is an automotive-grade platform with an MPAM 1.1 compliant MSC on the DDR egress path for system-wide bandwidth QoS. 2. The typical scenario is preventing memory-bandwidth-sensitive workloads from saturating DDR: isolating bandwidth between infotainment and ADAS domains, and preventing background services from starving latency-critical workloads. 3. We verified on v5 (with the top-level memory controller MSC node as a direct child of the root): - MSC probe from DT (dmesg: MPAM enabled) - resctrl mount with L3/MB/L3_MON resources - MB allocation through schemata writes - Dynamic throttle change while traffic is running - MBWU monitoring (mbm_total_bytes) - Monitor assignment across multiple groups Usage log showing the memory controller MSC working through resctrl on our board: root@hobot:~# mkdir /sys/fs/resctrl/group1 root@hobot:~# echo "MB:0=50" > /sys/fs/resctrl/group1/schemata root@hobot:~# cat /sys/fs/resctrl/group1/schemata MB:0=50 L3:0=ff root@hobot:~# my_app & root@hobot:~# echo $! > /sys/fs/resctrl/group1/tasks root@hobot:~# cat /sys/fs/resctrl/group1/mon_data/mon_L3_00/mbm_total_bytes 1314 # Dynamic throttle change while workload is running: root@hobot:~# cat /sys/fs/resctrl/schemata MB:0=100 L3:0=ff root@hobot:~# echo "MB:0=20" > /sys/fs/resctrl/schemata root@hobot:~# echo "MB:0=100" > /sys/fs/resctrl/schemata root@hobot:~# cat /sys/fs/resctrl/schemata MB:0=100 L3:0=ff The bandwidth throttling takes effect immediately on schemata writes - verified by observing the DDR bandwidth counter drop and recover in sync with the throttle level changes. Thanks, Ping